Yours is a common problem, as Pat said if he is food motivated you are in luck.
Besides the watch commands, I start by teaching all my puppies to TARGET TO MY HAND. Very easy & fast to teach. I would start by making sure every bite of food he gets is from your hand (include your oldest son in this training to overcome this fear.)
Step #1 Put a treat in your hand, open palm, let him eat it (simple) repeat this several times.
Step #2 Treat in open palm, move hand to left or right. When he follows it let him get the treat. Repeat both directions, up, & down. When he is following the treated palm consistantly procede to step 3
Step # 3 Put treat in palm, close your hand, if he looks at your hand, open your hand & give him the treat.
Step #4 (Closed hand with treat) Move hand to left, he follows he gets treat, move hand to right, he follows he gets treat. Simple!
Step # 5 Time to start moving. (Don't put the leash on since you could get tangled & you don't want to remind him of a learned behavior like dropping his head when the leash is attached.) Start with the treat in open palm & have him follow it as you move around, give treat. Work up to treat in closed hand as you move around. Be sure to hold your palm down because this is how it will look when you have a leash in your hand.
After you have praticed this until he will follow you with head up put the leash on.
Step #6 Attach leash, if you are good with the leash roll it up in your left hand, put the treat between your thumb & forefinger. Show him the treat & start moving, reward when he gos for the treat. DON'T let him jump at the treat, keep it right above his raised nose. Now put the treat in your closed left hand, fingers down, just above his head. Start moving, when he follows open your fingers & there is the treat! Work up to moving fast, changing direction, make him catch you for the treat (you should do this off lead too.)
If you have problems with the leash, work them out beforehand. You can also start by dropping the leash & letting it drag behind. You can also hold it in your right hand until you both get the hang of it.
I don't use a verbal command other than to say the dogs name & "GOOD DOG". In the Show ring nerves can kick in & having commands to remember as well as everything else can cause a meltdown. Keep It Simple Stupid (KISS) is my motto!
Until he has this new behavior imprinted in his mind I would give every bite of food from you hand. Remove the dog bowl! All food comes from hands not inanimate object on floor!
Best of luck, but remember that good conformation is only part of Showing in Conformation. Attitude plays a big role. I have seen many beautiful dogs who never finished because they hated showing. I have seen not so great dogs with lots of attitude finish quickley.
Have fun, this excercise helps with Agility, Rally, & Obedience too. Will improve your WALKIES too. Attending an Agility or Rally class will help build his confidence.

Becky