One month. However, you will most likely have to pay the closing costs out of pocket. Refinances done within a year go off the sales price, not the appraised value. If, however, you wait at least 1 year, we use the appraised value. Now, that may still require you to pay closing costs at closing because the value may not have gone up in one year. Better to wait at least 3 to 4 years if you want to roll everything in (it depends on the escrow - if any). Also, the best time to refinance is after the taxes/insurance (depending on which is higher per year - think FLORIDA) have been paid for the year. The next question would be: Why are you doing a loan that would require you to refinance in the future, especially that much sooner after you buy? Maybe you should reconsider buying the house before you go and spend another $4000 plus refinancing.