The earlier the better for anyone who hasn't made up their mind to buy Bitcoin and hold it for the long term base, but also financial education is very important even more important than having the money to buy Bitcoin, so before you place the buy order, consider it to be of an essential aspect to always acquiring.
There are still people who invest in bitcoin for the long term just for the sake of their children's education in the future someday, they start now from a low price by means of DCA or whatever it is that can buy to accumulate their portfolio because education is very important and requires a lot of money not least so for those who pin their hopes on bitcoin for its future it would be far better than storing in inflation-drained fiat.
There are also those who are still unable to invest because they are hindered by the cost of their education now so every time they get a salary, it is only enough for the needs and costs of their children's education.
The most important aspect that must be prioritized, if you want to invest in bitcoin long term then at least there must be a reserve fund in a few months, then they can start investing slowly by DCA.