Technically, the NFL released the OTA and mini-camp schedules for every team, but you don't care about those. From the good people at NFL.com:
Clubs are permitted to hold a rookie minicamp on one of the first two weekends after the NFL Draft and conduct one mandatory minicamp for veteran players. Clubs with new head coaches, however, are permitted to conduct one additional voluntary minicamp for veteran players. There is no restriction on the number of minicamps a club may hold for rookie players.
The dates for your Houston Texans' OTAs and mini-camp are after the jump.
OTAs: May 21-22, May 24, May 29-31, June 4-7.
Mini-Camp: June 12-14