This site states this specific instruction directly: because memory support takes weeks to judge, write down your deadline the day your order arrives.
Worth reading "because memory support takes weeks to judge" as this site's own stated reasoning — the 60-day window and the multi-week evaluation period make tracking your exact deadline especially important.
Mark the specific date your order arrives, calculate 60 days forward, and set a reminder well before that deadline to allow time to request a refund if needed.