Can anyone lend some strategy advice?

These are my last 2 cards and I believe my team is going to finish first! I've never gotten a Wild Card or first in these races so l was wondering if anyone can tell me if I should Wild Card my 4-star sticker and hope the 5-star I need is in the pack? Or do it vice versa? I'm not sure which card pack they make you open first!

Help! I'm anxious! Thanks in advance!