Ask HN: Solo founder and MVP. New co-founder equity split?

I am a solo founder looking to bring on a co-founder. My original idea came to me over a year ago and I've worked on it evening and weekends. Four months ago, I left my job to work on my startup full-time. I'm in my early 30's and my background is in investments and software. After college, I was a software engineer for two years before moving into asset management in a front office role. My product is built on the domain knowledge I gain in this area. It's B2B SaaS with target ~$15k-$100k p.a. revenue per customer. I've finished my MVP and am about to go full tilt into sales mode. I would love to bring on someone to do sales. I'm in early stage discussions with a potential co-founder who is a friend and someone I have worked with. He's in his late 20's and recently completed an MBA at a top school. His background is in business strategy and analytics (sales focused). He hesitates when it comes to sales because he does not see himself as a sales