I'll share some notes from our trainer, she's great. Lucky had the "down" in no time by using this method.
Your Down position is one of great patience and you folks did great with this yesterday – encourage your puppy down with your antics and your hand motions. Always give the support on the rump to anticipate they may pop up. If you need to help them then take your arm over their shoulder placing your left hand on their left leg and your right hand on their right guiding them down while your left elbow rests on their back for support.
Don’t be too quick to slip their legs out for them – give them a moment to recognize what direction you want them to go in. Guide them only if you feel they are not focused on you. ONLY if you are helping them down, give them a compliment and release and praise immediately until they go down on command then begin to build up your time. Using a toy for the more mouthy pups is going to help you obtain the position in a much more comfortable way – the trick is to use the toy the first time, and not the second – on the second rep – give them the toy once they are down – and then use it again on the third rep. – begin to mix up when you will use the toy, so they don’t become so dependent on it and will go down because you have asked them -
Your goal is a 1 minute down with you standing up next to them. Gradually increase your time and once you get to the 1 minute – it will become (3) one min. downs in a row, just like the straight sit. Give them something to chew on while they are down so they don’t get too antsy and grab onto you or the leash.
Remember dogs will gravitate towards sound and motion. Give as much of yourself as you can to animate them into position.