刚刚把refinance的贷款文件翻出来看了，上面这样写的

At least one borrower will occupy ,esteblish, and use the Property identified above as my/our principal rsidence within 60 days after the execution of the Security Instrument and shall continure to occupy the Property as my /our pricipal residence for at least one year after the date of occupancy, unless lender otherwise agrees in writing.

看来也可以和lender协商取得lender的同意。