This migration guide advocates a one-way synchronization from SVN to Git during the transition period. This means that while your team is getting comfortable with Git, they should still only be committing to the original SVN repository. When you’re ready to make the switch, the SVN repository should freeze at whatever state it’s in. Then, developers should begin committing to their local Git repositories and sharing them via Bitbucket.
The discrete switch from SVN to Git makes for a very intuitive migration. All of your developers should already understand the new Git workflows that they’ll be using, and they should have had plenty of time to practice using Git commands on the local repositories they cloned from Bitbucket.
This page guides you through the final step of the migration.