Knowing when a beginner project is finished enough to stop polishing and move on

My small command-line project works, has basic tests and solves the problem I built it for. But I keep finding reasons to rewrite it: cleaner abstractions, prettier output, one more option. Three weeks later I've learned plenty but haven't started anything new. For a beginner portfolio project, what's a reasonable definition of done? I'm considering a README, a handful of test cases and one tagged release, then deliberately moving on.