21 year old college student looking to house hack at UC

[Jacob Scott Hecker]

Hello, Bigger Pockets. I have been fiddling with the idea of house hacking around the Univerity of Cincinnati. I see how much my roommates and I pay in rent each and every month and I still currently have 3 years left at the university so I figure I may as well have that wealth coming into my own investment. 

I have been checking out Zillow just about every day for the past two months and new houses do get posted every once in a while. But what I have come to notice with being in such a hot market the houses that I would potentially want to buy get picked up in as little as one or two days. 

I don't exactly know what to do because I would need to go through the mortgage process for the house and there isn't enough time because someone has already picked up the house. So then I thought about getting pre-approved for a mortgage but then I discovered this usually only last for 60 to 90 days. In this timeline what if nothing comes and I want to simply just have that money waiting for the deal to come up so I can move on it quickly as I need to after that 60 to 90 day period. 

I have about $15,000 to use as a down payment that I have saved up from my Co-op money as well with a 740 credit score and I could also get my parents to cosign because they have always been more than supportive of my business ventures in the past. So I don't believe getting approved would be my issue. 

Any advice or anyone who has done this same process before please let me know.

Thanks!