Fine Tune Heeling?

Rewarding him a little more often may help. Give him a treat for being in position, before he begins to drift. Watch him carefully and continue to treat him, before he drifts. You can easily stretch out the treats and have him heeling wonderfully, with some practice. He's just a little guy. It sounds like he's doing really well.

One option used by Patti Russo is to do an about turn halt.  It prevents forging.  Another option is to do left about turns.  Start practicing heeling with only 3-4 strides. Stop play, pet, praise,etc,  Then start again.  Precision heeling (OTCH level is really beyond a puppy this age if you are going more than a couple of strides).  Another option is to find a secure area (fenced).  Get some REALLY REALLY good treats that are not used for anything else.  Go into this area off lead. Wave the hand with a treat near your dog's nose.  Then  you wander about without paying any attention to your dog.  As soon as your dog is one your left side, stop (make sure your legs are not together; most dogs learn that position as "sit") and feed the puppy a small piece of treat.  While the puppy is chewing/gulping turn left INTO/toward the dog, so you are now going in the opposite direction.  This automatically forces the dog out of heel position.  It becomes the responsibility of the dog (if they want that treat) to find heel position again.  As the puppy gets the hang of it, start moving very erratically.  Your puppy will soon learn heel position is where the cookies appear.

Thanks to both of you for the advice. I appreciate it very much and will give it a try. I wasn't sure where he should be in regards to his age. He seems very smart and picks up things easily, but I don't want to "nag" him.