When/how can I put in to change positions?

Since my PL is some sort of cryptid only spotted every other full moon that falls on a Tuesday I'm asking here: first, when can i put in to change positions? Like I've been a cashier for a couple months and I want to move to stock, is there a time I have to be a cashier before I can even do this? All I remember from training is minimum 6 months for team lead positions. Also, is there a way besides the broken webpage for career preferences to do this?