Beware of valuations and fixed-splits!
Valuations at this stage are futile. They wild guesses about the future that will never be true (you'll either fall short or surpass your expectations).
Similarly, a fixed equity split will set you up for future problems. A fixed split is when chunks of equity are doled out at the outset of the venture. For instance, he might propose a 50/50 split. This is fine when nothing has happened, but what if you do all the work? What if you want to bring in another partner? What if he expects you to pony up the cash? What if you do pony up the cash and you spend it all?
Every time something changes, you will have to go through a painful renegotiation of your split.
Use the Slicing Pie
model instead. The Slicing Pie model ensures that each person's % ownership of the equity is equal to that person's % of the risk taken.
Slicing Pie is a dynamic model that guarantees each participant has exactly what they deserve.
I've written a book about how it works. Contact me through SlicingPie.com and I'll send you a copy. Read it before your meeting!