you can calculate online your page rank ... you can calculate how many backlinks you need... see more http://www.check-rank.com
About time. How much it depends on you. How does PR work? Make as much backlinks and incoming links as possible. What's more backlinks should be preferably from the sites with high PR. Having link on such site you get more share and your PR is improved by that sharing!Then comes qualitative content, updating and good managing of your site...
I have seen our backlinks jump to 400,000+ and a couple of months later drop to 56,000. Then after submitting some "real" press releases to a few hundred industry sites we then saw our back-link count drop to 54,000. Where's the credibility when you see stuff like this happening all of the time?
Google does not reveal all the factors in takes into consideration before giving a PR, but the age of the site, and the authority of its backlinks is taken into consideration
The fact that a site has age and is the original authority on a topic should be enough. But to have created such a site built upon innovation after innovation and then find that you no longer appear in search results simply because monkey-brains have created junk advertsing sites around your keywords is not just ridiculous, its absolutely disgusting and we have the likes of Google to thank for that. Submitting a site to lots of directories to spam keyword popluarity is not something that should ever be considered as ranking criteria... any monkey can do that. In fact almost everything that Google has introduced into search relevence has been so stupid that a legless dog could find ways of exploiting it. Google's algorithm is a joke.
PR is made up many internal and external factors. Internal factor means hows your site, how many pages in your site? and external factors means how many link to your site. PR of site depend on traffic of your site. Google gives the PR to site on its traffic. If your site has a more traffic you can get more PR. If you want to more traffic on your site you must create number of links that are links to your site.
If you have enough back link then you must get better page rank on google search engine. Sometimes page rank tools shows wrong series and it hampers to our mind. Don't worry about that things.
Quality of the links coming into your site, and the number of them. Quality is essentially determined by the number of links coming into the referring site.