This proves to be in line with the market, but I like to err on the side of caution and use lower numbers.

Would I have to wait a certain amount of time to prove positive income on this house's cash flow?

I'd need to really study up on exactly what this approach might entail. 

Since everything else was fine and my file was clean it was just the proving of my payments that was a problem.The higher review approved the loan with me providing a signed affidavit about the living situation.So talk to the underwriter and see if there is any way you can get your file "bumped up" the food chain.

I've even upgraded just to prove that I'm serious!!

I graduated from college with a BA in Liberal studies and a minor in Communication.

I'm very skeptical though of all this as the history proves that as soon as the tax incentive disappears so does business.  

Chicago is basically the perfect mix for this type of study because it's highly desirable areas, densely populated and reasonably affordable (although definitely not cheap).For instance, I would expect New York to be #1 in millennial renters, but prices are just too high for millenials to buy. 

I'll take the former, especially if it is a mentor who is recommended by someone I trust who as 'been there done that and has the scars to prove it'. 

But, in the meantime, I am studying and researching right here on BP; and, await @Bob E.