Our dog has probably just come out of puppyhood/adolescence (she is 15 months). For the 1st 6 months I reckon looking after her took 2-3 hours a day (spread throughout the day). There is no way I could have left her for more than 2 hours. From about 8-20 weeks she slept quite a lot - but needed constant supervision & feedback about her behaviour when she was awake. At about 20 weeks I started to see some benefit of all the work I had put in. By 7 months she was properly listening to me. I went to a lot of classes from about 12 weeks (ie; as soon as she could go out). My husband & I also spent a lot of time discussing how to bring her up. I have to say that I don't see how looking after a puppy (esp. a sick one that hasn't had the best start in life) could be compatible with work (plus I doubt they would let you take in one w/ mange). We work from home (we are bike mechanics) & hence work downstairs & have really tolerant bosses (ie; ourselves). I did almost no work during the first 4 months we had her as I looking after the puppy - everyone I met in the park said it was just like having a baby.

Don't be tempted to over-exercise the puppy to give yourself an easy life - it's much better to exercise their minds & it's just as tiring. The rule of thumb is that walks should last 5 mins for every month - so by 3 months, that's a 15 min walk.

Best thing we did - crate train the puppy, and be 100% consistent with feedback (ie; decide what the rules are & stick to them no matter what).

If you decide to go ahead, find yourself a knowledgeable mentor & lean on them - we had the breeder of our puppy. It's surprisingly mentally challenging - all the owners of the puppies in our litter really really wanted the puppies, were experienced & had spent £800 on a puppy. Despite this, pretty much every one considered returning the puppy at some point during the first 6 months. Having said this - I think it depends very much on breed (we have a Hungarian Vizsla - high energy & apparently very difficult puppies) - I met a very easy 4 month old golden retriever & the breeder said he was typical of his breed.