Today, Friday, I got 4 phone calls at 3pm PST asking if they could buy health insurance for a match Saturday. Two of the Bastards were from Florida!!! (That's 6pm EST for the Props)
C'mon people. Get a fucking clue. I'm gonna type it one more time:
YOU CAN'T BUY HEALTH INSURANCE ON FRIDAY FOR A MATCH ON SATURDAY!
Underwriting can take 2 to 12 weeks. Mostly because your MD won't release your records to the insurance company in a timely fashion. Fixing this is easy. (Later, I'll link a pdf form letter here that y'all can download and use.)
And yes, technically, your policy date is the date you signed the app, but you're assuming that you get approved. And if you health status "changes" mid-underwriting, who knows what the insurance company will do.
Don't risk it. Don't be stupid. Buy Health Insurance!