After checking over my list, can confirm that six chairmen (myself included) are yet to pick. Will give them until 11 pm BST tomorrow, otherwise I will randomly assign them numbers and we shall move on.
Hadn't set a hard deadline for picking numbers (since I want to make sure everyone picks one), but let's shoot for 11 pm BST tomorrow.
You can use the perk whenever you want to during the season. Of course, if your perk is a transfer related perk, it can be used only in the summer and winter windows. Perks dealing with facilities and balances can be used whenever.