Hi OP, yes by the time he was 12 weeks he could sit, stay, lie down, fetch, come and walk to heel. I'd like to think it was because he is a genius but I think labs are really bright and biddable.
I felt really confident taking him out when he was tiny knowing that he would sit and come back by the time we took him out.
Alto's idea about the bell to signal needing to go for a widdle is a great one - we taught our chap to stand with his nose on the door when he needed to go out!
And ours fetches his lead and collar when you ask him ... And likes taking things to different people in the house so DH and I often give him notes to take to each other and to visitors - he loves learning people's names and showing off! It's also quite handy when I can't be arsed to find DH to tell him dinner is ready!
I agree about the jumping up though - people tended to encourage him to jump when he was small which made it hard to get him to stop but they learn a lot from withdrawing attention - ie ignoring him when he does stuff that you dont like - which seemed to work.
Other than than, I'd just say be really clear in the words you choose for each command, repeat things to reinforce the meaning and have tons of fun as that'll keep your little woofer interested. FWIW, we started off training with treats but then realised that strokes, cuddles and going nuts clapping and praising him worked just as well as a reinforcer. Made us look slightly bonkers but we didn't mind that too much!
How exciting!!!! Not long to go now!
Xx