It all depends on the quality of the links that points to the site for example a week or so before the last update I launched a site called
Promote your website for only A Pound , I have just two links pointing to it from a very good source and the site got PR3 .
I also launched another site at the same time but that one did not get very good backlink and it never got any PR
So it really depends on how good the links pointing to the site is. The site you launched a few months ago will definately get some PR, the most recent one as well if you have a number of good link pointing to it it should get some PR as well.
Thanks