Timeframe for Links To Have an Impact On SERPs

[Industry]

After Google indexes a page with a new inbound link (or series of links)to your site, how long before the benefit of the link is seen and may affect the rankings? I realize one link will likely have no effect, but let's assume this is not a very competetive term, Company A is on Page 2 for a term, Google indexes a number of key text based highly ranked pages with a link for that term....how long would it be before you would see any bump in the SERP's?

[wheel]

One data point. I registered a keyword rich domain in May 2010. Over July/August I got about 3-4 on topic relevant links, all with the exact anchor text of the domain name.

In the first couple of months or so it landed on about page 3 for the exact search. In the past week it has leaped to spot #2.

So, in this case, 1-2 months for a bit of effect, 3-4 months for full effect?