Sexual assault of child. Makes outcry after moving out of now 17y.o. suspect's home, but unable to give exact date of assault(s). Suspect's 17th birthday is right in the middle of the range of possible dates of the offense. Any thoughts on how to proceed?

This response assumes continuous sexual assault doesn't apply due to the 5-year age difference requirement (Tex. Pen. Code Ann. 21.02(g)) and the all-acts-must-be-committed-when-over-17 requirement (Tex. Pen. Code Ann. 21.02(b)(2)):

A few options:
(1)Attempt to have the juvenile court certify the defendant to stand trial as an adult on the crimes that happened pre-17th-birthday. Indict with a grand jury on post-17th-birthday crimes. Then try both cases together in adult court.

(2)Seek only a grand jury indictment on the post-17th-birthday conduct and use the pre-17th birthday conduct as evidence in the trial. (How far your judge will let you go in using the pre-17th-birthday evidence during g/i is your call, but there are several very strong appellate arguments for letting it come in during g/i.)

(3)Keep the kid in juvenile court and seek a determinant sentence, using the post-17th-birthday stuff as punishment evidence showing a need for TYC+TDC time. (I personally hate this option. In my experience, kids who commit sex crimes are just ticking time bombs that should be locked up for life because "rehabilitation" rarely works in such cases.)

Note: Check out Brown v. State, 381 S.W.3d 565 (Tex. App.---Eastland June 28, 2012, no pet.) (online slip opinion) for details on how one prosecutor got around the "I can't remember the dates" problem by getting the victim to describe the location of the incidents, from which the jury could deduce a reasonable timeframe.

what about Section 54.02 Texas Family Code? Which is not a certification, but just a discretionary transfer.