I'm afraid you should take the time to improve your credit before you undertake the responsibility of homeownership. It's unlikely you'd be approved for a mortgage loan with those scores. Best to put your financial house in order and prepare for the homeownership experience the right way: with decent credit.
That being said: why is your credit score so low? Is there a chance we can increase that credit score?? Do you have balances on credit cards pushing the scores down?
With a VA loan it is the credit score and the why with the credit score.
You do need to discuss with a mortgage banker or direct lender that does not have a 620 minimum score (which is where most mortgage are limited).