If those dates don't work for people, there are other companies to look into for training in this area.
Extreme Pyrotechnics - in Mansfield, they could probably be talked into doing a Texas training class if there is enough interest, although they are open to just bringing someone directly onto a shoot site for training, if they see your potential beforehand.
Pyro Shows in Fort Worth - March 5th and 6th
Illumination Fireworks - Carrollton - I am sure they will be doing local training before July, maybe try watching there facebook page.
There are a few other companies who do work in this area, but those are probably to easiest to get setup with training in this area. Also, do not be afraid to call these companies and talk to them about working shows, even if they do not offer a set training class.
Please understand that most of the companies will want you to work a show for them around July 4th, which can be a good learning experience, but will also be a lot of work, and pay will vary with each company and experience. Some may pay a basic day rate to all crew members, while others may only buy you lunch and give you a free tshirt in trade for working that first show.
Also, I would recommend signing up for more then one companies training classes if you can, as all have there own ways of safely doing things and you would be wise to look at a few different methods for safely dealing with these kind of fireworks.