How to pressure test your fulfillment & shipping before peak: a practical guide with Shippo × ShipBob

Peak season can expose every weak point in your operations. Andy Hopper, Principal Solutions Architect at Shippo, and Francesca DeCastris, Senior Partner Manager at ShipBob, share how to pressure test your fulfillment and shipping before BFCM. Their tactical advice covers how to simulate spikes, track weak points, and build resilience into your stack so you can deliver on time, even when volumes surge.

Why pressure testing matters

If you wait until peak to “flip the switch,” you’re setting yourself up for failure. Andy points to the example of ASOS, a UK fast-fashion retailer that went live with a new warehouse management system without fully testing it. The rollout caused inventory chaos, undelivered orders, reputational damage, and an estimated £25 million in losses.

“A failure to plan is a plan for failure. In shipping, if you don’t plan for failure, you are planning to fail.” – Andy Hopper

The takeaway: pressure testing protects both holiday revenue and long-term customer trust.

Stress test your fulfillment accuracy and speed

Many brands focus on speed under pressure, but neglect accuracy. Wrong-item shipments drive returns, drain margins, and erode trust, with error rates as high as 50% among self-fulfillers that lack warehouse processes.

Here’s how to pressure test fulfillment properly:

• Look back at historical spikes
  Pull data from your last “stress moments”—flash sales, Prime Day, coupon codes, or influencer-driven surges. Compare actual SLAs vs. promised ones. Did you hit same-day fulfillment, or were orders delayed? Did error rates climb during those peaks?
• Run a creative mini-sale now
  Launch a one- or two-day sale with enough demand to stretch your ops. Watch how your team performs on order accuracy, packing speed, and throughput. This lets you find bottlenecks before the holiday rush.
• Audit cutoff times
  Check whether orders received before the cutoff (e.g., 2–3 p.m. for same-day shipping) consistently ship on time. If there’s slippage, it’s a red flag you need more staff, automation, or better carrier pickup coordination.
• Track carrier performance under stress
  Don’t assume carriers are reliable just because they are most of the year. Monitor delivery scan times, delays, and error rates across each carrier. During BFCM 2020, USPS delays forced some brands to switch carriers entirely.

“If you’re self-fulfilling, don’t underestimate how much efficiency comes from how inventory is placed in the warehouse.” – Francesca DeCastris

Build resilience into your shipping workflows

On the shipping side, resilience is about planning for both digital and human failure points. Shippo’s test API token makes it possible to simulate load without incurring costs, but systems also need to be designed around rate limits so they don’t silently drop orders.

Ways to optimize your workflows:

• Build for carrier failover
  Don’t tie all volume to one provider. Set up alternate carriers (regional + national) and rules for automatic fallback if your primary carrier goes down or hits delays. Yes, it may cost more — but it keeps promises to customers.
• Validate addresses earlier
  Move address checks to checkout or order ingestion instead of waiting until label creation. This removes friction at the worst possible time and reduces last-minute failures.
• Design smarter error handling
  Use retries with exponential backoff, and escalate errors after a defined threshold instead of retrying forever. Let your system keep processing other orders while a human investigates the failure.
• Measure the human layer
  Time how long it takes to print manifests, carry bins to the dock, and hand scan forms to drivers. Bottlenecks aren’t always in code — they’re in workflows.
• Create and rehearse SOPs
  Document what to do when labels fail, tracking doesn’t update, or carrier pickups are missed. Run dummy packages through these processes so the team knows the playbook cold.
• Automate failover rules
  Add triggers like: if a label takes more than 30 seconds to generate, reroute to carrier B automatically. Automation reduces reliance on humans during critical moments.

“Don’t make humans the failover system. Automation has to be part of your resilience plan.” – Andy Hopper

Work with your 3PL on cutoffs and contingency plans

Cutoff dates vary widely between 3PLs and marketplaces, and Amazon’s are often earlier than others. Get those dates early and publish them clearly on your website and in email campaigns to set expectations.

Relationships matter too. During peak, problems are inevitable, but having a named account manager who knows your business can make the difference between a quick fix and days of disruption.

“Pay for account management even if you don’t qualify — it’s worth it during peak.” – Francesca DeCastris

How Our Place added $2M in holiday revenue through smarter shipping and fulfillment

The cookware brand Our Place scaled seamlessly during holiday peak with Shippo × ShipBob:

• A two-person ops team managed six warehouses worldwide.
• Each additional cutoff day added about $500,000 in revenue.
• Distributed inventory saved over $1 million in freight costs and kept 98% of orders in low-cost zones.
• Achieved half-day average fulfillment and 2.5-day delivery during peak.

ShipBob handled fulfillment, inventory distribution, and intelligent routing, while Shippo powered the multi-carrier shipping layer. Together, they gave Our Place the technology and operational velocity to scale smarter — meeting peak demand without adding headcount.

The peak-prep checklist

Every brand should run through this checklist before peak:

1. Optimize your warehouse footprint

• Place inventory closer to customers to cut zones and delivery times.
• Ask your 3PL to run heatmaps showing where your orders actually ship to.
• Consider splitting SKUs across multiple regions if your volume allows.

2. Stress test beyond pick/pack

• Receiving and stowing delays cascade into order backlogs. Track how long inbound pallets take to be received, labeled, and shelved.
• Run a dry test where you “pretend” 2x the normal inbound volume arrives — can your systems and team handle it?

3. Know your weak points

• Pull error-rate data across each stage (receiving, picking, packing, shipping).
• If your 3PL can’t give you historical SLA data, ask why — that’s a red flag.
• Track not just averages but worst-case outliers to know how your ops hold under stress.

4. Run “game days”

• Simulate a scenario where your primary carrier is down — how fast can you reroute?
• Pretend one of your API endpoints is throwing errors — does your retry logic keep working?
• Double order volume for a day — does your system scale or stall?

5. Document SOPs

• Write clear step-by-step guides for what to do when labels fail, carriers delay, or inventory mis-scans.
• Share them with your team before peak, not during the chaos.

6. Rehearse with your team

• Ship a dummy order and deliberately create a “tracking not updating” scenario. See if support and ops teams know what to do.
• Assign roles: who escalates to Shippo? Who calls the 3PL? Who updates customers?

Want to learn more?

📘 Further reading: The complete guide to building your fulfillment tech stack

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