Don't know about budswell, possibly a gimmick. A good rule for repotting is once you get past the seedling/rooting stage, put it in a 1-3 gallon pot for vegging, and transplant into a 3-5 gallon(bigger if you want) about a week before the flowering phase.
Depends how fast you grow.
We can't accurately predict how well your plant is going to do, and give a timeline on which to replant, but by looking at pics and reading replies, you should be able to get a 'feel' for when you should do it, by comparing your plant, or asking if it is time, when you think it might be.