No one knows that. It depends on site index + Quality BL's + Page relevancy Cpl of times I have seen PR for a 3 days old site
Don't think so. Couple of my sites which had no backlinks what so ever gained PR 3 or more in a lot more time than those which had some Authoritative Back links from Higher PRs . But all these take time and don't happen over night for sure. A lot of factors go into it, but dun think it's time constraint. All Success, ~G
There is no minimum period for G for that PR....By the way The links you see when you check the backlinks from Google doesn't really the true backlinks of the site it is just some links....