Visitors to your blog decide to stay or leave within seconds of arriving at your blog. Your blog’s layout is one of your biggest and most visible decisions you will ever make, so be sure to make the decision wisely when it comes time to decide whether to change it or not.
The most basic of questions you should ask yourself is: Does it really need to change? Just because your favorite theme developer comes out with a new theme, does not mean your blog needs to switch to it. Nor do you have to change the look and feel of your blog just because it has been 6 months since you have changed it. Some of the best websites and blogs haven’t changed their look in years.
Your blog is about the content.
So when do you change the look and feel of your blog? There is no hard and fast answer, unfortunately. One answer is whenever you add something “major” to your blog such as a new service or feature you want to heavily promote. Even then, you might decide to only create pages for that new section rather than redesign your site.
I admit, I used to try new themes every few months. Now, I have a different approach. First, I find a theme I think will fit the site for the next year or two, install it, and make the necessary modifications to it so it comes as close to my current “ideal” as possible. Later, once the blog is established and is generating content, I do a complete analysis of top pages and readjust that theme, making tweaks here and there. Once the site is becoming more and more active, with more visitors, then and only then, do I look to see if there is a better theme that would help my visitors, or I commission a custom theme.
Changing your theme, even if to a better one will be a definite change for your readers, and some people simply do not like change. Grow your site, grow your content and change the look and feel of your site only when necessary.