Basically, I think that it is worth investing in bitcoin today and at any other time. But if we are already talking about the date of financing such an investment, in the short term - say, within a few months - the exchange rate may change many times. It is only in the long term that such investment seems more certain. We're talking about years - maybe two, maybe five. The rule could be reduced to the following: if we want to earn on bitcoin in the short term, we will have to find time to be up to date with all fluctuations. In a few years' perspective, we can simply grow the value of purchased crypto currencies.