Is there a way to calculate exact app launch time measure on iOS?

I am trying to measure app launch time from appium server events api via driver.getevents() and filter time duration on cmd launch app but this logic not measuring exact times noted with actual apple provided app launch measure ?

Does anyone have exact idea of calculating the app launch time exactly via appium ?

Best way is to have Developers instrument the debug build with Xcode and log times. The way you are doing it is better than nothing, but as you state, it’s somewhat imprecise.