That depends entirely on yourself.
I usually wait to see what a coin is doing on the exchanges.
But if you really want to (stake) or get a discount on the purchase.
Then as soon as possible. But then you can still be deceived.
Because if the value for any reason decline's like crazy, it could be that you see half or more of your investment vaporize.
On the other hand, if you wait to purchase any coin and you see that the value goes up.
Than the purchase you are thinking about also gets more expensive in that way.
Although I'm not a professional, it is my experience that a coin will first fall before rising again this is probably due to sharks selling there assets.
Which then results in a dump and most crypto's do not survives this.
Unless the community is stable enough, than the coin recovers and stabilizes again.
But that lies with the community that has been attracted during the development of the Coin / Token.
Whatever choice you make, please realize that you are responsible for the choice you make and no one else.