
You wouldn't shop at the grocery store and assume you can afford everything in your cart just because you had some money last week and expect more income soon. You'd check your bank balance before you got there so you'd know how much you could spend that day.
Shopping for houses is no different. Before you tour a single home, you need to know how much you can afford to pay. Not guess, not assume. Know. Unless you're going to pay cash, the only way to do this is to sit down ahead of time with a mortgage lender.
Why is this important? If you find a house...