The best time to sell off your crypto investment is either when the market value of the crypto coin you invested goes a bit higher than the initial value you invested or when the value drops to avoid you from losting a greater portion of your initial investment.
yes that's good enough because you sell when the price is higher than when you start investing.
Crypto values can change at any time so you should be able to take advantage of opportunities when Crypto rises and you have to take them quickly because if you are a little late you will regret it.
Crypto movements can change very quickly, so be careful when taking action.