How do I put a limit on my decks to show up before exams?

Hi guys I’m very new to anki, and I don’t know how to add a limit or due date for my decks so they can all show up before my exam by a day or 2, I’d still like it to show up normally after the exam so I can retain then knowledge, I also make my own cards so I don’t if it’s because of that?

Thank you!!