how can i do a backtest of a option strategy?

I may have fucked up based on previous replies from my thread.

i did my research but maybe not thorough enough.

i opened 30dec2022 long strangles on spy going into FOMC and CPI data. i was looking to at the very least, sell before on monday close. and maybe close on tuesday close before full FOMC annoucnments.

based on last 2 results, from what i know, there was a sharp uptick. but its based on very crude/manual backtesting.

what is the best way to do a backtest? to get better clear numbers on IV, and stock price at very specific times of the day, etc?