Nope, even if we script it to flash right when you press start, it will not make much difference because it will be switching to the 1st map right away anyway and the scene transition from title to map will be in the way making it flash black briefly. If you set your event to run on parallel, it should be running before you enter the map scene, so i don't see why it's "too late".
edit:
and oh, you will not be using your 1st map as a "playable map", but simply use it as a picture shower/story teller(Set your 1st map to be the same picture as your title if you want a good looking flash effect here).
Do your flash and whatever there, then when all the play sequence is over, transit to your real play map and set your player character to visible.
So 1st map = opening, not play map.