I recently started a blog on building insurance as I have some experience in this area. However with Googles page ranking speed and the fact that I am in a competitive Keyword area I don't think my inbound pr 4/ pr 5 links will credit me with a similar rank in less than 6 months. And as I mentioned My keyword competitors with their established websites/blogs are also strengthening their PR, so as I stride 10 steps forward they may well be striding 12 steps forward. I've talked to may bloggers about this and they too find it frustrating in regards with PR and PPC. I think 8 to 12+ months is the realistic norm if one is starting from scratch.