I know the question might be a bit silly but I have 3 sites that I have ranked with spam backlinks. It took about a week for the kw-s to appear on the second page of G and then they just stay there fluctuating couple of spots up or down. This has been for weeks, I constantly add in the links but it's the same. Funny thing is that there are blogs with 0 backlinks to them on the first page that are even not entirely optimised. I have the kw in title, desc, H1, url, alt tag etc. The density is around 2,5% on the overall page.