I made some on page SEO changes to my friend's website. Funnily enough he has a bunch of good text links coming into his site but the on page wasn't targeted at all. Now that I've put a few relevant and low competition keywords on his site, how soon til the changes might be reflected? I just used pingomatic and bookmarked the site to reflect the changes, just wondering if he'll see a substantial difference in rankings for those words and how long it might take.
With new Google feature Caffeine, changes may be seen on 4 days. If your site is popular just wait a few hours.
... or if the site didn't change frequently and the links haven't changed for a while it could still take weeks. Get a couple of more inbound links (even fairly low quality ones) and it should happen more quickly.
Google takes time to give results for every effort and if you have backlinks for your site than it is good for your site.