I try to do at least 4 restocks over a 24 hour period for one round of token shop items. Like said, the initial restock is always announced in the news. I've done some restocks where it'll last over a weekend (I think I did that during Luminaire or New Years) and when I do that I specifically say in the news post "hey this will last a few days". I've been doing restocks once a week though of bringing back old items + sometimes adding a new item here and there. :)