When do you buy the dip?

One major problem of trading is buying at the right price before pump but how do you know the dip? I have seen this phrase many time and i mostly ask how do you know the bottom? Imaging $pi listed this week on some exchange including bitget and dip to $0.7 but currently trading above $2.1. Despite huge airdrop of the project, many speculated it will dip to about $0.01 before any major positive trend but seem the token defiled btc dominance with it recent price trend. This further made me ask the question when do you know the dip. I have understand that market is based on speculation and predictions and users need to do his personal research to make the right decision and when to sell or buy is solemny his decision. This is why most influencer advise to invest what you can afford to lose so you don't panic or fomo. Anyway, could there be a better way to understand the bottom of a token?