Anything that affects the traffic to your blog, such as any change in the URL, affects the success of your blog. Publishing the blog to a custom domain, like renaming the blog, will affect traffic to your blog. The effects of the change will vary from blog to blog, because of the different traffic to every different blog.
- Followers. People who find your blog because of recommendations by other people.
- Search engines. Robotic processes which methodically surf your blog, and provide dynamic indexing to people who search for information.
- Subscribers. People who read your content from their newsfeed reader, such as the dashboard Reading List.
- Viewers. People who read your content from their browser.
The differing combinations, of traffic sources, will make every custom domain migration unique. You cannot predict what will happen to your blog, during the migration - but you can plan, and improve the experience.
Planning and executing the migration properly will help your blog recover faster, from traffic loss caused by the URL change.
- You'll start with a new URL, which will be unknown by the search engines. Your blog won't get as much new reader traffic, until it's indexed, under the new, non BlogSpot URL.
- You'll end up with a better known blog, with a non BlogSpot URL - and more new reader traffic because of the new, non BlogSpot URL.
When your blog has a new URL, that URL is initially unknown to the search engines, and other web services. The search engines, and other external web services, index by URL.
- With a new blog, you have no content, no readers, no search engine reputation, and no statistics.
- With a new URL, there is no indexed content, and no statistics.
- With a blog recently republished under a new URL, you have content and readers - but no search engine reputation, or statistics, under the new URL.
If your blog has its own search engine reputation, it gets indexed by the search engines, directly. As the BlogSpot URL of your blog is indexed, the "301 Moved Permanently" redirect, from the BlogSpot to custom domain URL, will contribute to reputation for the domain URL.
If your blog has readers who link their blog to yours, your blog gets indexed by the search engines, indirectly. As a readers blogs is indexed, and a link to your blog is found, the link to your blog is followed. Readers blogs that point to the BlogSpot URL, again using the "301 Moved Permanently" redirect, will similarly contribute to reputation for the domain URL.
Each of the various traffic sources - people (Followers / readers / subscribers), and robots (search engines and other automated services) - will contribute, in different ways, to the indexing of the domain URL.
Before you start, understand the right way to purchase and setup a custom domain. And understand the nature of, and need for, the 3 to 5 day Transition Period, which follows the purchase of a new domain, using "Buy a domain" - and should be observed with any new domain.
During the migration, you'll find:
- You'll get better results from a properly setup domain. Always start, with a properly setup domain.
- You'll find the diagnostic utilities in Google Webmaster Tools to be essential, in helping you objectively observe and correct any problems.
- As search engines index your blog, they adjust their indexing to follow the rate that you publish. If you publish weekly, they will, at most, re index your blog weekly. The less often you publish, the less often the blog gets re indexed.
- The entire blog won't be re indexed at one time. You'll always have new posts, that have not been individually indexed.
- While re indexing of the blog is in progress, you'll have some posts indexed under the BlogSpot URL, and other posts indexed under the domain URL.
- As additional posts are indexed under the domain URL, those same posts will drop from indexing under the BlogSpot URL. If this were not so, you'd end up with "duplicate content" penalties. The purpose of the "301 Moved Permanently" redirect is to avoid this duplication, and penalties.
- With the indexing of the blog split between the two base URLs, the reputation overall will be lower. You get better reputation with all content indexed under one base URL - and this won't be the case until the migration is complete.
- With lower reputation, your posts will have poorer SERP position - some posts indexed under the old BlogSpot URL, others under the new domain URL - though all SERP entries will get your readers to the new domain.
- With poorer SERP position overall, you'll have a period of significantly less search originated traffic.
- The more often that you publish, during the migration, the more you'll compensate for the drop in reader traffic.
- As the blog is re indexed under the new URL, reputation - and Page Rank - will pick up again.
- You'll observe activity, in Webmaster Tools, for both the old and new URLs, for a while after the domain becomes active.
- Some tools, used under simple blog renames, are not used with custom domains. Specifically, custom domain publishing does not use the post feed redirect.
You cannot avoid the new domain transition period, and reduced traffic level - you will have to endure it. In the end, if you manage the migration properly, you'll find that it was worth it.
With a new, properly setup non BlogSpot URL, more blog content, and the same reader population (forwarded from the BlogSpot URL), search engine reputation (and Page Rank) will pick up and should continue rising, beyond where it was before you started the migration.