I would recommend your first step would be to contact your lender.
There are many variables when you are applying for a loan and locking in an interest rate:
* How long have you been employed at your current job?
* Your debt to income ratio.
* Your credit scores (FICO's)
* Price of home your purchasing
* Time frame of your purchase (as rates change)
Once you have your answer on what type of a loan & interest rate you qualify for, you should ask for a pre-approval letter from the lender.
At this point, an area Realtor will be able to look for properties that match the guidelines of what you can or cannot afford.
Best of luck!