Q4 is the most important time of year for most eCommerce brands. Black Friday, Cyber Monday, and holiday shopping drive 30-50% of annual revenue for many categories. A fulfillment failure during this window is catastrophic — not just in lost sales, but in the negative reviews and brand damage that follow.Preparation starts in September. Here is what to do.**Forecast Your Volume**Look at last year's Q4 data and your current growth rate. If you grew 40% year-over-year, plan for 40% more volume than last Q4. Share this forecast with your 3PL in September so they can plan staffing and capacity.Be honest about promotions. If you are running a 40% off Black Friday sale, your order volume will spike dramatically on that day. Give your 3PL advance notice of major promotions and the discount depth so they can estimate volume.**Pre-Position Inventory**Send inventory early. The worst thing that can happen during Q4 is running out of stock. Build in a buffer — if you think you will need 1,000 units, send 1,200. Carrying extra inventory for 6-8 weeks costs much less than a stockout during peak season.At 3PLCity, we recommend clients have peak inventory on-hand by October 15. Do not wait until November.**Communicate Promotions in Advance**Tell your 3PL about every planned promotion — date, expected volume, any special packaging requirements (gift wrapping, promotional inserts). The more lead time, the better prepared we are.**Packaging and Supplies**If you use custom packaging — boxes, tissue, cards — order extra before peak season. Supply chain delays are common, and running out of branded packaging in November means shipping in plain brown boxes.**Customer Expectation Management**Set realistic shipping expectations on your product pages and cart during peak season. If orders might take an extra day, say so. Customers who expect 3-day shipping and receive it in 3 days are happy. Customers who expected 2-day and got 3 leave negative reviews.