L.M.
Every kid is different but if you are going to give him a snack before bed make it something like crackers w/ cheese or peanut butter, celery w/ cheese or peanut butter, a piece of fruit or some veggies, a piece of toast w/ peanut butter. It is something light and except for the fruit or vegetable it is giving him a bit of protein.
If he's just stalling, you should be able to tell because he will probably decide he doesn't NEED a snack. Also, let him have the snack at 7:30-7:45 so he has time to brush his teeth and still make bedtime. After 7:45 it is a no go.