June will be my daughter's 4 year gym anniversary. In that short time, she's gone from complete newb at 5 hours a week to training level 9 for 30 hours a week.
Granted, 30 hours is high. On average, I think hours will max out in the 20-24 range. But, they do ramp up pretty quickly- especially if you're in a fairly competitive JO track.
I was clueless where we were headed for the first two years. I don't know if it would have changed anything, but I do wish I had at least some clue to the time and expense involved before she got so...well....obsessed.
Yours is only 6- I feel pretty sure she could be easily steered another direction. Of course, it may take a little tears and a little time, but nothing like it will after a couple more years.
So, yes, decide now!