Making sure your financial plans are in order is essential to do prior to searching for a home. Understanding what sort of requirements you will need for your lender is important. This includes w2 requirements, (being able to show proof of w2 income for 2 years) or (being able to show self employment income for 2 years) if you have a downpayment making sure it is seasoned, etc… Getting preapproved before you start your search will help define your parameters so you do not waste you time, or your realtors time searching for a home only to find there are mitigating circumstances that will prevent you from buying it. Understanding the cost of your loan (how much closing costs will be approximately) is also important. Preapproval letters indeed do expire after a short time. Some listing agents are okay with a preapp letter that is less then 90 days old, some want one that is less then 30 days old. It all varies. Answering your question, yes getting preapproved for a given amount now will help you realize how much lenders are willing to commit to you. Understand this value will vary as interest rates change but unless those changes are substantial, that amount will not change a whole lot.

Also understanding exactly what your house payment will be including insurance, property taxes and any other homeowner expense is important before you do your search as well.

Once you have all of the financial stuff in order and estimated you can then start to look for a home with the confidence that there will be no surprises down the road.