I would be very careful with that statement, myself. There are some schools that that want you to report EVERY single ACT score you've written and some of the top schools actually say that they'd prefer that you take it no more than 3 times. Yes, a student could probably hide their poor scores from these schools, but why chance having them find out and recind their acceptance? I personally wouldn't take that chance.
I guess it depends on the type of school your dd is looking to attend. If she's looking to attend a school that's ranked academically in the top 50, then I'd say, hold off until she's ready. No need to rush. This after is after all a marathon and not a sprint. It's a very loooong journey with many ups and downs (as I'm finding out myself). Schools do not expect freshmans and sophomores to have scores. If you have them, great. But many do not expect them. Coaches at top academic schools will tell kids to take the ACT no later than the Spring of their junior year for the purpose of seeing if this kid is within their academic parameters and if needed, the kid could retake for a higher score.
But to answer your question, it's better to take it when the student is prepared and will do well rather than to take it simply for a number to stick in the box. A great score will get their attention because they'll know that the kid will be admitted when the time comes. Having any ol' score in the box is NOT going to get the kid any more attention than having a blank box.
Just my 2 bits.
There are a few exceptions to this. One of my nieces needed to take the SAT while in middle school for some sort of summer program for gifted children.