You can get your Florida mailing address without establishing a domicile. Its' just a place where you have mail sent, not where you live. At any point after that, you can use your mailing address to establish your domicile. We got our address about 3 months before we domiciled. We changed our address to the Florida mail service on our credit union account, and a couple of weeks later printed off a credit union statement with that address on it. We also changed our cell phone address to the Florida mail service address, and printed off a statement. A couple of months later, we had those statement copies, along with all the other documents needed to establish Florida residency, and took them to the county clerk office in Florida to get our vehicle tags, drivers licenses, and voter registration on the same day.