My baby was 12 weeks old when I got him, but we really should have waited just a little longer. Our breeder was great, and let us take him, but if I had to do over again, I would have let her keep him for at least another month.
He's only 4 pounds (full grown), so he was a tiny one at just 12 weeks.
I guess it just depends on what you and your breeder feel most comfortable with doing.
And, yes, pee pee pads worked well for us whie indoors, but we trained ours to go outside after they started to lift their legs.
Good luck!!