If I will attach my new blog to my signature here. How long will it take before I could have a page rank?
1 link is not sufficient.. You need more links to visually see the green bar in the google toolbar... Google will update the pagerank maybe once in 2 months or so... (Nobody outside google knows this - i think) Just check this out.. http://www.seocompany.ca/pagerank/page-rank-update-list.html
Google is always updating Pagerank behind the scenes, the visual Pagerank value we all can see is usually updated every 3-4 months, or 4 times a year. Yes, actually in theory 1 link could provide a Pagerank value, if a PR10 page linked to you and your the only outbound link I would assume you'd get a PR1. Build more backlinks; that is the key to building Pagerank.