OP, just HODL Bitcoin, and you wouldn’t have to worry “when to exit at the appropriate time”. Because at the “right time”, no HODLer would need to sell their coins. Bitcoin will be accepted EVERYWHERE. It’s starting in El Salvador, and it’s not going to end there. 
Of course I hodl Bitcoin but I had to go into investing on these altcoin as I couldn't afford to purchase 1Btc at a time. So what I literally do is take profit on these altcoins and buy more Bitcoin regardless of whatever price its sitting.