PR is a waste of time don't bother with it Rankings in SERPS (searc engine resuls pages) is all that mathers Time it depends on competition and effort
I have to agree with w3bmaster, PR is not the most important thing. I would rather be in first position for my keywords than to have a PR8.
Depends on how hard you are working on your site and when google will update PR next. They dont tell us when they are going to update.
I disagree with saying PR is not important, if you are doing adsense, then you might found that the high PR site are giving you more revenue. Besides, if you want to sell your website, people will always ask for your PR