Ppto question prolly confusing srry

So I work 1-10pm I clock in at 12:51 I want to leave early like around 6:51. Will the ppto count the 9:51 time when I usually get out or will it need to be directly at 10pm I’m putting ppto in for 4 hours starting at 6:51. Don’t know if it counts the 9:51 time.