When are the "Time To First Draw" values recorded?

histogrammedOptimizedTimeToFirstDraw and histogrammedTimeToFirstDraw are both described as the "time taken to launch the app" with/without pre-warming. But, after we measured these values in production, we found them to be very similar, maybe a few hundred milliseconds apart.

We expected the pre-warmed, or hot launches, to be far faster than the cold launches since the docs state that pre-warmed builds execute an app’s launch sequence up until, but not including when main() calls UIApplicationMain().

Which leads me to ask, what do these values truly represent?

When in the launch cycle of an app are they captured?

Thank you!