Employee #1 - how to structure/write my own ESOP offer?

Hey all, I'm about to join a *very* early-stage startup as employee #1. The co-founders and I have already agreed in principle that I will be getting a fixed $amt translatable into shares (for the sake of discussion, let's say $500K). The number of shares will be pegged at the valuation of the next funding round, which is set to occur fairly soon. Again, for the sake of discussion, let's say that the post-money valuation cap of the upcoming round is $5M. My share would translate to 10%. But it could be $10M and my share would be 5%, etc. This would be vested monthly over 4yrs with a 1yr cliff. I've been asked to draft my own ESOP proposal to this thing. How would that look like? Given I'm to be the first employee, should I get a discount relative to the funding round (20%? 50%? 90%???). I've asked close friends in the startup space but they've never been this early stage where there's not been a priced round to peg share count, valuation or strike price to, so their own templates don't quite work for me. Any help or direction people can point me towards would be greatly helpful. Thanks!