Keep 12 BTC and wait...

That will depend on your view of Bitcoin and where things are headed. The most bullish on Bitcoin adamantly believe Bitcoin will serve as the world's payment rail and that Bitcoin will unearth all existing financial and legal systems. Those bullish expect Bitcoin to hit $10k or $100k+ in the next few years.
You can sell right now and you will earn a nice 6k at least. The choice is up to you can also wait to earn more coins. So you can sell right now or wait for the price to get higher.