Gitlab Installtion conversion from Source method to Omnibus/package method and Upgrade to Lastest version


I am on a Gitlab source installation (version 6.9.2) on RHEL 6.
I want to convert it to Omnibus installation and upgrade to latest version (8.2).
Can some one guide me to good documentation/steps.
Are there any best practices or any thing we need to take care, before embarking on this activity.

Thanks in Advance.