I got married last year on 4-25 and sunset was at 7:57pm (or something like that). That, coupled with the fact that daylight savings begins on March 17th next year makes my vote for 7:45 pm. Have a great wedding! Oh, and from experience, if you have your wedding outdoors in Houston, definitely have a backup plan!
According to the calendar I found, it will be @ 7:45.http://www.sunrisesunset.com/calendar.as��
It would be closer to 7:45PM. Daylight Savings Time has already started by then.