Welcome to YT!! You'll find a ton of very useful and resourceful information here for your yorkiebaby
Make sure you read through the 'stickies' (first few posts on each forum page), especially in the general training forum.
I can't comment on the potty training of such a young pup because we got Scottie when he was a few months old.
But I do know, as it's been recommended already, that a puppy that young needs to be fed more often. At such a young age, free-feeding would be a good idea. He's growing and needs lots of fuel and nutrition!