Hmmmm....! I believe the best answer to this question would be to refer this question to a Mortgage Lender/Broker as opposed to having it answered by a Real Estate Agent! The reason is because Mortgage Lenders work directly with Banks and Financial institutions/companies who actually loan the money, and who set the prerequisites and requirements for the actual loan approval! This relationship qualifies them to have more direct knowledge of the minimums needed for loans to be approved and/or not approved.
That said, there are a number of things that you can do, in the meantime, to start building credit; however, the actual qualifications and criteria for getting a mortgage are usually based upon your amount of income, debt to income ratio, job tenure, savings, down payment, and of course credit score(s)! I have preferred lenders that I work with that would be more than happy to help you sort things out! Please contact me if you would like to know more! - Thanks!