Picture the room settling down, the first toast going up, and nobody at the table stressing about the tab. Pulling off a milestone retirement dinner at a seafood spot takes a bit of lead-time, especially if you want that private room.
You have about two months before the date to lock down the space and talk through the menu. Getting ahead of the timeline means you can space out the cost instead of watching your checking account take a brutal hit all at once.
Keep in mind that the 0% intro APR for 15 months on purchases and balance transfers is a deadline, not free money. If you still have a balance left when those 15 months are up, the normal interest rate kicks in on what is left.