That question has no answer. Playing better isn't a function of the number of games you've played. It takes practice over time. Plenty of people play for many many years but don't get better. Some practice a lot in a short amount of time and see improvement.
Similarly playing at 1200 doesn't take a set number of games, but a set of skills. Basics like tactics, developing your pieces, and not hanging pieces mostly. If you don't want to learn, you can happily play 10,000 games and not get any better (I know a few people with over 50,000 blitz games who have stayed at the same level for years).
When I say potential I mean the point where you are at your best and cannot be any better at chess at any other point in your life.
How many games do you think it would take to reach say, 50%, 70%, 80%, 99%, etc, of your potential?
By 500 games how close do you think you should be to how good you can be?
How many games should it take you to be able to maintain a higher than 1200 rating in blitz if you are an average player?