I noticed a bunch of timers began at different times, so to keep timing consistent I tested the loading screen time by counting frames with frame advance on emulator, and found that this game takes 2.90 seconds (174 frames) to load. As normal reference, Super Mario World takes 2.20 seconds (132 frames) to load. This difference is usually most affected by custom music but level edits have an impact as well. Hope this helps!

Thanks a lot for the help Dode, this will help a lot for the coming runs.

So we can start at -2.90 seconds from hitting 1P Start to get the timer at 0.0 when we gain control of Mario?