It's actually whenever the person who makes the script feel like making the script. The script can also be made prior to the event ending. Also it's like 2-3 line code PER tier so don't think they are working hard when making a script to give out spender items take no more than 10 minutes. Script simply selects all users who meet requirement then inserts item. Not like they do it manually one by one... Also let's not forget, this isn't our first spender. All they have to do is edit the rc value/carat value spent and the item id. They probably aren't even making the scripts from scratch every spender despite being 2-3 lines long.