Setup a test site beforehand no matter if you're antsy now and decide to "just do it" or wait 5-6 months the points being;
- A test site i.e. yoururl.com/testvb/ is allowed per the license agreement, it must be .htaccess protected so it's highly advised to use this to your advantage.
- Testing on a cloned database typically shows you the same errors encountered during a live site upgrade.
Use the test site after it's upgraded to 5.x format to tweak your style, modifications etc and on that note - not all modifications will carry over to 5.x or styles for that matter so be sure to do a test site and prepare yourself and your site in advance

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