Whats the best age..

to introduce a puppy? (For those with experience in new baby, and training puppies) My son will be 9 months, and we've been looking into getting a puppy so it can grow up with him. I'm a SAHM and feel I have the time and patience right now. I was honestly ready for baby #2 but SO wants more time. We have a 5 year old lab who's very well behaved but it's my boyfriends dog, and she's not exactly a family dog. She only wants to be around him, and doesn't even bother with my son. I've been wanting a smaller dog for awhile now but was waiting for a perfect time.. any suggestions?☺️I'll take any advice; good or bad.