Personally, I believe that the best moment to purchase any cryptocurrency is when the price of the token you want to purchase is low, so you may sell when the price rises. Another occasion is when a project is just getting started, such as when I invested in Paragen $Rgen, a just launched project built on the Binance smart chain. It is listed on pancakeswap and CMC, which was part of my study. It's a multichain metaverse incubator that's worth considering in the long run.
So I believe those are the best times to buy, at least for me.