The answer totally depends on you. It is a subjective matter. You can hold as long as you want to, and you can sell now if you are already happy. Maybe one of the key points to know when is the best time to sell is to remember what is your main reason why you entered crypto? Are you here for the short term only? You just want to trade and scalp? And then you are good to go? Then probably you should sell the moment you already profited and you are already happy with your profit. Because after all, trading and scalping are really time and trend based. You wouldn't want to be late in selling your coins.

Or are you here for the long term? Do you intend to be an investor for good? If so, then you can just wait until you see the ATH of bitcoin before withdrawing your funds. You can also withdraw once in a while so that you can also enjoy the fruit of your labor and patience. Just remember to leave a reasonable amount to your portfolio and just touch what you think you need. It would be much better if you will allot a specific amount solely for investment purposes and do not touch it for any other reason aside from what you really intend it for, the first time you invested. Honestly, it all really depends on you. Just be disciplined enough so that you won't be regretting later. Remember, you can always enjoy today without robbing your future self.