Thursday night
The Order Happens Thursday Night
Placing an order is the easy part, and it's also the only part with a deadline. Get it in before Thursday turns into Friday, and you're set for that Saturday.
Here's the detail that trips people up if they've ever done a CSA or farm share before: nothing is charged yet. There's no card on file, no deposit, nothing held against you. You're reserving a spot in this week's harvest, not buying anything yet.
Once the order's in, that's it for Thursday. The next time you think about this is Saturday morning.