I have made important SEO changes as per your suggestions to my site that should rank me higher in the search engines. How long does it take to start seeing the first effects?

Assuming that you have implemented a sound SEO strategy, you can expect the following time lines:

* Site wide internal link changes can take a few weeks to kick in
* Single on page improvements should be picked up a couple of days after the bot visited your site.
* Inbound link effects can vary widely but as a rule of thumb: once the bot finds your link, and actually reaches the target page it'll take roughly 15 days to see the changes in effect.

These figures are a worst case scenario. You usually should see uptake quicker, but shouldn't worry either if it takes as long as the figures above state.

The more popular your site, the faster your service and the more traffic you get, the quicker your site will be indexed.