How old is your puppy? Are you taking him out immediately after he eats or about 10 minutes later? Are you crate training?
With Angel, I would wait about 5-10 minutes after he ate. BUT, he was NEVER out of my site. If he didn't poop and pee, he went back into his crate. The next time he came out was right to his pad for his duties. For me, crate training was the easiest. He trained in about 2-3 weeks! Last August I took away his pee pad and now he goes outside. He never poops right after he eats, though! He is now 2 years old.
Also, when you take him out to poop, make sure you walk him around, keep him moving to stimulate his bowels. When Angel goes out for his duties, he is always on a leash, that way he knows it's not playtime. So far it works!