It's normal for BTC to drop before making new highs. Just hold and enjoy the ride
The question is for how long does one need to wait? You understand the feelings of going to your wallet and seeing your money on losses for a longer period of time. For instance you hold to sell in 90days, but by 75days you enter into losses that seems irreparable within the next 60days.
So, it is not as easy as you think to just hold on.
You are simply asking a question that only you can answer, do you need anyone to tell you when you have to sell your coins? It's your fault if you already make huge profits and failed to take the profits, that's example of been too greedy