I'm a fan of GitHub but from what I see GitLab has some neat features I'm not technical enough yet to really use.
Ever since GitHub allowed private repositories, I switched a few repos from Bitbucket to Github, which has better issue tracking. I think Github and Gitlab are both about the same for casual programming.
Looking back, it was important for me just to keep making commits and not worry about the technical stuff. Given that there are good tutorials on how to move a repo from one website to another, I wouldn't worry too much. If you catch yourself saying "I wish Gitlab/github could do this" then maybe it will be time for a change. But I know I got more mileage out of learning how to use git, e.g. cherry picking commits with add --patch or learning to use branches. And learning how to make good commits has helped with my programming habits immensely e.g. not trying to do too much at once, testing each commit, and so forth.