so smart! you must be good with training so the "come" and "stop" should come easily. the trick i have used on 2 past dogs plus my new little dexter is to keep treats with you when outdoors and give them a tiny bit of a treat everytime you call them and they come. practice when there are no other dogs around if you have her out at a park and slowly try it closer and closer to other dogs. i find dexter (4 1/2 months) will now not even be interested in going to play with other pups until he sits beside me and gets a treat and i tell him he can go play where he used to just take off running after anything that moved!
i find it takes on average about 3 days to almost fully get the concept that "come" = treat...depending on how much time is dedicated to the training. i have used this on a chinese crested, lab and yorkie and had worked wonders on all 3!
good luck and im sure it will be a breeze with such a smart baby!