Hi Pavi,
I think I answered your question on FaceBook but incase you did not get it:

Unfortunately, for Quesadillas it is best cooked last min

You can, however, try this a couple of days ahead and see how it works:
make the Quesadillas ahead and then put them in a single in the oven (on broil) and heat for just a couple of minutes each side and allow them to crisp up and serve imm.

Try this out BEFORE the party and see how it works out – this is a suggestion, we have never tried it but think it will work.

Happy Birthday to your son and Happy Cooking!