Does it have to be Thursday? Friday is when the Apple Stores (or Authorized Resellers) give you drop-in discs... for free.
Buy the MacBook on Friday.
Otherwise, pay the $9.95 for the up-to-date program.
I will be purchasing a MacBook on thursday. Will Snow Leopard be in the box or can I ask for it seeing as it's a day before? What do I do?