New Software Engineer with questions about investment properties

[Ziva Hirsch]

Hi, I'm new to this forum and I want to start buying investment properties in the US and I'm about to start a high-paid silicon valley software engineering position in a few months. I have a signed contract. So I have 2 questions: 

1. How soon can I get approved for a mortgage? I've been a student until now so I don't have any previous income. 

2. I have an investor/family member who is going to be a part of these investments and he's a multi-millionaire - how does the process work to have him as a financial backer when applying for mortgages? He's not a US citizen (I am). Our longer term plan is to make this a business and have 30+ rental properties. What's the best way to show our partnership when applying for mortgages so that the bank sees both of our incomes? 

Thanks so much.