Kirk was 34 in TOS, so he would be 24 in Discovery time.
Kirk, Spock, McCoy, Scotty - post academy. McCoy was an MD and didn’t attend academy.
Chapel was either in the academy or post academy.
Sulu and Uhura were probably in the academy.
Checkov and Rand were probably pre-academy (despite Grace Lee Whitney’s age)
thanx I’m lazy poster