go ahead and list the one you are wanting to sell. In the meantime, find a house in the new state and write a contract with a contingency that you cannot close unless the first house sells. There needs to be a time limit because the Seller will not want to be in a "pending" status for a year waiting for you to sell. This can be tricky, especially if you aren’t able to swing two mortgage payments at one time.

You just have to write a contract stipulation (contingencies) that meets your needs when buying a new house and selling your old one. You can even get financing to cover your expenses during the transition (equity).