<human>: So I've been helping a guy I met from my other job out with his startup on the sales end. I have another full time(ish) job but I make my own hours so I've been doing about 15 hours of work for him every week. Recently he told me he liked my work and wanted me on board full time and could give me a base salary to get me to leave my other job. 

So the base isn't too great (35k) but the commission is ridiculous so I'm totally down. Me and my other boss have been fighting alot recently and I'm more than happy to leave my other office to work for him full time. 

Problem is I want to start full time around the first week of september but I want to know I'll be getting paid immediately. His company is very new so initially he expected me to come in full time for 100% commission and I told him I couldn't do that and expect to pay my bills. So he's offering the security I need but I'm a little worried that he might not have the cash ready when I want to start and I don't want to waste time there. 

First off, how do I bring this up politely without sounding too distrustful. Also what should I be looking for in a contract?

Could you distill the essence of the text into 1-3 sentences?
<bot>: Guy offered me base salary to work at his startup. I'm not convinced he has the funds and want to make sure I have a contract between him and I before I start working there full time, essentially leaving my other job.