And for those of you that have, Texas has a weird 'delegate' system for the political parties. So after the polls close, you need to return to the caucus convention at your precinct and vote again! This helps determine how delegate votes are distributed for the candidates.
You can rest assured I'll be showing up for the caucus!
The caucuses begin statewide (7:15 PM) fifteen minutes after the primary polls close or the last person votes at that location. (But that's if polls close on time, media is speculating with the unporecedented early voting turn-out, election day turn out may also break records, and if the polls are very crowded, they may extend voting hours.)
Most of caucus locations are at the same place as a persons poll. However to sure, check your location here: http://www.sos.state.tx.us/elections/voter/county.shtml