Reserve stock a few days before delivery

Each move carries a computed reservation date. Once that date arrives, two things can reserve it: the daily Procurement: run scheduler job (it runs every day and takes due moves oldest-reservation-date first, starred first within a day), and the automatic re-check that follows any validation of related stock. Between confirmation and the reservation date the transfer just sits at Waiting with its availability pill telling you what the forecast looks like — a yellow Exp date is normal and healthy here. If you cannot wait for the nightly run, Check Availability on the transfer reserves it on the spot regardless of the countdown; and in developer mode an administrator can run the whole scheduler by hand from Inventory › Operations › Run Scheduler.

Nothing reserves on the day — check the scheduler cron is active (Settings › Technical › Scheduled Actions › "Procurement: run scheduler"); it is the engine of this method.

A transfer reserved earlier than the day count says — someone clicked Check Availability, or it is starred and the starred day count is larger.

Starred transfers behave no differently — days before when starred is still 0; the star only changes the countdown if its number is bigger than the normal one.

Everything reserves at midnight of the same day — both day counts are 0, so the countdown is "on the scheduled date"; raise them if you want a buffer.