i think trying to train a puppy at such a young age, to sit, stay, down, ect, is maybe asking too much, as puppies have a limited concenration span 
, at a young age, and could become bored,by asking too much of it!!
I have to disagree. I think its very important to begin some basic training, as you described, from when they come home at 8 weeks. I agree that a puppy's concentration span is limited when at a young age but it is still perfectly possible to train them to sit, down, stand, leave, give, stay, fetch from the off. They key is to keep the sessions very short, varied and very upbeat and interesting so they don't become bored. It might be just 5 minutes in the ad break of Coronation St when you a couple of repetitions of sit, stand, down as an example. Reward as you go but I also reward after the session with a quick play. And they are more than capable of learning at that age, as an example with my last puppy, Morgan, at 9 weeks he could do a down on verbal command without lure and could fetch a soft toy.
Keep it short and varied, repeat it often during the day, keep it upbeat and make yourself interesting, reward each wanted behaviour and at the end of the session have a short play session. The whole session, including play reward, could last just 5 minutes but its invaluable to your pup.
