When does the trader reset?
With the standard three-day interval and a Day 1 world anchor, restock days are Day 4, 7, 10, 13 and so on. Server configuration and mods can change the interval, so the calculator leaves it editable.
What the calendar does not know
The site does not connect to your save or server. Blood Moon range, warning, airdrop timing and modded schedules can differ. Enter the intervals actually shown in your world settings.