I agree with the others that it's best to wait with some of the advanced training until the puppy is older and attention span a little longer lol
But, in my experience, it works well to teach drop/sit recalls by leaving the dog in a stay and moving out a distance. Call the dog to you and when they reach you, give sit/down command. Back up a few steps (say stay if you need) and call again. This has worked with all of my dogs and is a very gentle method. As you keep doing this, gradually you can give sit/down command while the dog is a little further from you until you can go the full distance you'd like call and give the drop any time you like and the dog will obey. Other good thing is that this doesn't require a second person if it's not convenient at the time you're training. ^_^
Good luck.