Hi rjohnson, I'll be upfront with you................520 is way low and I am not aware of any lender who would be willing to work with you until and unless your credit score improves. Even if you were fortunate to find someone it would cost you by way of of the higher interest rate they will charge because they will consider you higher risk.
As you have not owned a home previously, you might be able to qualify for a first time homebuyer's downpayment assistance program of up to $25K but you must have a minimum credit score of 660 to qualify. My suggestion would be to get working on improving your score. If you have a relationship with your banker you might want to go in and speak with a loan officer there, or a credit counselling center to see what you need to do to get to where you want to be in the shortest possible time. If you don't have someone to work with I would be happy to put you in touch with some experts who
can help you. Feel free to contact me for further information at 407-864-3139, or firstname.lastname@example.org