Start with a clean baseline
Historical sales may include stockouts, deep discounts, unusual ad spend, or one-time events. Mark these periods before calculating normal demand so the seasonal plan does not treat distorted sales as a repeatable baseline.
Add the event assumptions explicitly
- Expected traffic or demand lift by week.
- Planned price, promotion, and advertising changes.
- Conversion assumptions and inventory constraints.
- Production, freight, receiving, and contingency lead times.
- Post-event demand and the expected clearance path for leftovers.
Test both shortage and excess
A stockout can lose contribution and disrupt advertising, while excess inventory can create storage, markdown, and cash costs. Compare both outcomes in currency so the safety-stock decision reflects the product's economics.
Use staged commitments when possible
Smaller purchase releases, split shipments, or reserved supplier capacity can reduce forecast risk when commercial terms allow. Track early event results against the plan and adjust the later commitment before the full inventory arrives.