rrussell - 9:08 pm on May 5, 2008 (gmt 0)

Assuming your new site will mirror the content from your old site, the 301s should be tested thoroughly before moving your nameservers. I prefer to use individual 301s instead of one catch-all 301.

Here's a minor checklist, I'm sure others can elaborate:
- Check site: old-domain.com and make sure you've covered everything.

- Check webmaster tools for all pages with external links. Make sure that all of those have appropriate 301s to the exact page on your new domain.

- Use something like seo spyglass to help pick up more external deep links that you may have missed.

- Install a 404 script that will email you when you do make the switch and watch it like a hawk for the first couple of weeks for anything else you may have missed.

If you already own your new domain, great. Any age you have will help smooth the transition.

We recently moved a site in a competitive arena and were ranking on the new domain within two weeks... not months. Not to say you won't have some ups and downs, but google seems to pick up quite well on 301's IMO.