When my dogs poop I reward them with a single tasty treat. This encourages them to eliminate early in our walk or outing. There is a natural tendency for people to walk a ways and then turn back as soon as our dogs do their business. This is a bad habit to form, because the dogs will pick up on it and postposne going until they have walked a long distance. I make sure that once they go, I reward them with a morsel, and then we keep moving in the direction we were going for at least a block or so (or much longer if they do it early in the outing). It took a few weeks for Iggy to pick up on the connection, but now he goes within a block or two of leaving the house, then sits nicely for his treat and relaxes until I have gotten his mess cleaned up. Frankie still prefers to go in his own backyard, which is also just fine — I reward him there and I expect that over time he will make the connection and then will go on our walks.
I have also found that a little pumpkin (Tblsp for large dogs, tspn or less for smaller ones) with each meal helps keep them regular and on schedule. They didn’t like it a lot at first, but they got used to it within a couple days and now seem to really enjoy the sweet taste.
A few weeks ago we had very cold weather and snow here, and neither of my dogs revels in the cold — once Iggy went, he would actually turn in the direction of home and request to go back; often this occured within a block of our house. Frankie would go in the back yard and be ready to come back in within 2-3 minutes.