Again, gotta have income to get approved for a loan. Buying non-owner occupied isn't hard, but it does require money to budget to pay back the loan and a good bit of documentation. Before you have a renter. That means a job with verifiable income. There may be some info-mercial way of doing it that I don't know of.
$750 a month in rent isn't $750/mo in net income. Subtract the note on the house you want to buy (~$365 on 55,000 @ 7%), the monthly insurance ($40), taxes ($60?), maintenance, etc. You end up clearing a couple hundred or so for the month. When that a/c goes out, you've got to replace it, eating up the $200-300 you cleared each month. That's why, unless the house is free and clear, investors like this normally have 8-9 houses to be able to live off of just that. Most do it on the side. I have had many clients that do this, I see what they clear and what they claim on their taxes. You can do this, but I wouldn't substitute this for a regular job for a long time. Be prepared for a bank to ask you if you're going to college and how you'll make your payments and maintain the house during that time. Can be done, but that is what they'll be thinking.
I'm not trying to discourage you from establishing credit, just be honest with yourself about why you're doing it. Your 17/18, there's no rush. Most likely, they will require you to have a comaker no matter what, except for some credit cards.