Thanks for your description about timing, but there is one thing to note.

In this my video I deleted my saved data before beginning, but you don't have to take the trouble to delete your precious saved data. If you don't delete it, you should start timing when pressing NewGame+ ("Continue" after beating the game) or "Yes" to "Start the game again from the beginning?" (This sentence appears when starting the game halfway through).

Personally for me any which way is okay. Anyways, we must start timing at last select before the opening scene.