Hard to say, but I'm looking forward to growing mine out!
I saw some other fish from the same clutch and it would seem I selected the best one of the bunch. I'm only guessing, but I expect my fish to top out in the 9" area.
Personally I have only ever seen ONE JD that got to 10", and the biggest (but probably not full-grown) texas I've seen was about 8." All I hope for is that he won't wreak havoc on my 125 before I can get him his own space if need be.