After 6 months of living in Texas with the intention of being a resident, you are considered resident. If you have specific questions call the Texas Real Estate Commission. Below is a link to their application process. Getting your driver's license and/or registering your car, signing a lease, all these would help establish domicile and therefore residency.
You don't have to wait a year to become a TX resident, unless you are trying to receive in-state tuition for college. Because most, if not all, real estate institutions treat in-state and out-of-state students the same, this rule won't apply to you.