That’s hard to tell because nobody knows what the price of Bitcoin will be in future. Now, the price of Bitcoin is very low, so it is a good time to invest. But it is hard to tell when the price of Bitcoin will recover so invest if you can take the risk.
There is no particular time to know when to sell or buy in the crypto market because everything is based on choice of when to sell or buy. Where you may like to sell may another person point or price to buy. The rule is sell when you think it's convenient for you and buy when you think is ought for you to buy. We don't have to buy at the same place or sell at the same price because we all have different taste and the capital involved is different from one another.