Personally, I wouldn't wait until after he defecates to feed him again. He might not poop for 4-5 weeks.

Also, I would try assist feeding one bigger meal rather then a bunch of pinkies. More assist feeds = more stress. So if you only need to assist feed once per feeding, wouldn't that be more preferable?

I would try a fuzzy at least or a hopper. Pinkies aren't really developed enough to give the snake the nutrients it needs.