We use New Hope Christian School in Keller on Willis lane. They have an awesome program starting at 18 months with a room for each age group. My oldest started there when he was 2 1/2. They don't pressure them to be potty trained for the 3 year class, but most are. My potty trainig resistant child potty trained withthe schools help by Christmas. They have a "ball pit" area indoors to play in when it is hot, cold or wet outside. My youngest is 2 and he already knows colors shapes the alphabet,etc.. so great fun learning process as well.
If you are interested they do have a website. I don't have it with me right now, but I can get it.
The school is small, nurturing and flexible!!
Good Luck!