It depends on what your dd's aspirations are compared to her abilities.
This is the part that many parents do not look at, or refuse to look at. Parents have the rose colored glasses on and they let potential dollar signs blind them of the simple facts.
At what college level does/can your DD want to participate? What does she want academically? How far from home does she want to be? Those are the 3 big questions which will decide when to start showcasing.
The collegiate level of play will work itself out as she gets older and she realizes just what her potential will be. Academics will play a part in which schools have her area of interest.
You can attend college camps beginning at 10U. These are great for development and learning. As she gets older, it is a free look by a potential college.
Showcase tournaments....D1 colleges are looking at 13U and 14U for their recruits, little at 16U, and they look at 18U to check up on their verbals and potential recruits that they are still communicating with. D2 colleges are looking at 13U and up. D3 is looking at 16U and 18U. This is just a general guideline.
So, have you missed anything if she doesn't start until 16U....depends on where she wants to play (what are her desires?). Can she still get on at a D1 school? Yes, but she needs to attend their camps and get that coach looking at her. If she is a studette, then any coach, regardless of college division, would want her. It is just that the scholly money might not be there for her first year (D1 and D2).