You submit your homestead exemption in the first full year you own the home. So if you purchase a house in November 2008, you submit the exemption after January 1, 2009. Once it has been submitted you never have to submit it again until you move to a new homestead. Also, you usually have to do it yourself, its usually not done at closing, however they will often give you the paperwork you have to fill out at closing to take with you. Make sure your home is exempt, there are an amazing amount of people that forget to fill out the simple form and mail it in and are stuck paying extra property taxes.
The two times I bought a house in Houston and the two times I bought a house in Minnesota, I submitted it shortly after I closed. You don't have to wait until a new year to file.
