How did you buy the S&P500? Did u buy all at one shot or DCA?

Repeat after me: DCA, DCA, DCA

Textbook answer is time in the market is more important than timing the market. For me, I usually cut my pot of OA into 2: the first pot is for gradual buying where you do Dollar-cost averaging and the second pot is for buying during crashes. For example, during the recent COVID-19 crash in March and April, I placed a lot more money into S&P500. This is just my personal choice.