At some point in your piano playing journey you are probably going to want to play some of your music for other people. This might be a small intimate affair, or a large public concert. Either way it is important that you are properly prepared.
Nothing focuses the mind and brings a piece of music to perfection like a piano performance. Sometimes when we learn pieces of music they never seem to feel finished, there is always something more to perfect. Having a date when everything must be finished is really helpful.
A few weeks before a performance I always record my pieces and listen to them really carefully. I make a list of everything that could be improved. I then practice those specific things, and delete each list item as I fix the problems. This is psychologically really satisfying as my list disappears I feel like my piano piece is truly getting finished. I do this recording far enough in advance to make sure my piece will be truly ready prior to the performance.
Normally when I practice I often stop and fix things as I go. But when I am practicing for a performance, I make sure that most of the time I play the entire piece without stopping, and I practice keeping going even if something goes wrong.
I advocate practicing everything that will happen in your performance. Walking on and off stage, making sure you can play well in the clothes that you plan to wear, even practicing speaking if that will be part of the performance. I think it is absolutely worth over-preparing for your first few performances. That way they will be successful and performing your piano music will become easier and more satisfying.