It may seem self explanatory that you should not be spending large amounts of money while you are waiting to buy a house, but it is more complicated than simply what you have in saving. Remember your mortgage pre-approval is subject to a final evaluation of your financial situation.
Every $100 you pay per month on a credit payment could cost you about $10,000 in home eligibility. For example, a car payment of $300/month could mean that you qualify for $30,000 less in a mortgage.
Even if you have accumulated a substantial amount of savings, you should consider not making any large purchases until after closing. The last thing you want is to know that you could have purchased a new home had you curbed the urge to spend. And yes, that means you should wait until after closing to buy all the new furnishings for your dream home.