(from in directory original_repo)
cd ..
git clone --bare original_repo /outside_of_any_repo/my_remote.git
then 'my_remote.git' winds up with its configuration having 'origin' pointing back to 'original_repo' as a remote, with a remote.origin.url equating to local directory path, which might not be appropriate if it is going to be moved to a server.
While that "remote" reference is easy to get rid of later if it isn't appropriate, 'original_repo' still has to be set up to point to 'my_remote.git' as an up-stream remote (or to wherever it is going to be shared from). So technically, you can arrive at the same result with a few more steps with approach #2. But #1 seems a more direct approach to creating a "central bare shared repo" originating from a local one, appropriate for moving to a server, with fewer steps involved. I think it depends on the role you want the remote repo to play. (And yes, this is in conflict with the documentation here.)
Caveat: I learned the above (at this writing in early August 2019) by doing a test on my local system with a real repo, and then doing a file-by-file comparison between the results. But! I am still learning, so there could be a more correct way. But my tests have helped me conclude that #1 is my currently-preferred method.