Welcome, and congratulations on your new snake! It's generally best to wait a week or two before feeding to give them time to settle in, but if you wanted to compromise and go for Monday night (5 full days since you got him) it will probably be fine if he's otherwise satisfied with his setup. He should be eating small adult mice or at least fuzzies, though, as pinkies are too small and nutritionally inadequate. It sounds like you did your homework when setting up his home, and that's great to hear. How are you monitoring his temps and humidity?

Again, welcome and congratulations!