I have ordered new cheerleader uniforms and I forgot then missed the arrival time. Now I can't retrieve them.

When I go to the Priscilla's shop there is no button that shows up nor the Priscilla coming up to me and telling me that my order is here.

What can I do to trigger the event now?

Check the gym depot.
If you've talked to Priscilla, or somehow it skipped that step, the next step is to pick them up the following day from there.