I would like to know how long you see SERP changes after you put a quality link, ie a link from PR2, PR3 or higher. I'm seeing changes in about 2 weeks. You?
there is no exact date for that one.. but they crawl and index site regularly.. you can check your ranking maybe at least weekly or monthly..
It depends on the quality of sites you got your backlinks, those well-indexed sites like DP could make your site indexed from few hours to days. But the quality of the page your link resides matters too, like here in DP, you might get indexed from posting/replying in a thread but when the thread fades away, it effects vanishes too.
2 weeks is pretty good. Though most of the time the rankings are not yet stable.. and it may still go somewhere..