I have three on team, so I'll start with the oldest.
My 9 yo DD started at age 2 in a mommy and me class, as a birthday gift from grandma. She loved it, and moved on to preschool class at age 3, followed by advanced preschool at age 4. At age 5 she started developmental, but the coaching style was really harsh. It finally reaching a point where we couldn't take it anymore (there was borderline physical and emotional abuse and we were told DD didn't have what it took to be a competitive gymnast and would never have a spot on their team) so we switched gyms when she was 6.5. The new gym was wonderful, and she did a year of preteam and then moved to the L4 team. She just finished L5 and is beginning training for the "new" L5.
My middle DD (age 6) did a class at our former gym for a few weeks when she was a few months shy of turning 3. The instructor kicked her out for having a fear of skin-the-cats and forward rolls on the beam. Said she didn't have the right mentality for gymnastics and to stop wasting my money. (Kids who wouldn't try something or cried had to sit in the corner for class.) When we switched gyms, I decided to sign my middle DD up for a class. She was fearful at first, so the teachers let her tag along with me and her baby sister in the toddler class. After a few months, she was ready to be on her own, and joined a preschool group. In the fall, when she was 4.5 they suggested she try pre-team, not based on skills, but solely on body-type/strength/flexibility/speed. I decided to let her try, since we were at the gym a lot already with her older L4 sister. She blossomed in pre-team with good, compassionate coaching. My fearful timid girl turned into a fearless, hardworking focused little gymnast. At 5.5 she moved to L4, and began competing right after her 6th birthday. Now at age 6.5 she is training for the "new" L4, and already has every skill except the vault over the table. She is even working optional level skills on bars (her strongest event). She was the baby of the team this year, but the coaches say she is one the hardest working and most focused kids on the team. She LOVES gym and I'm so glad I didn't listen the the coaches at our former gym who tried to write her off when she was not even three years old.
My baby DD (4.5 yrs) never did anything at our former gym. She started in the toddler class at age 2 when we switched gyms. Then she moved to preschool, then Intermediate Kinder. She just tried out for the preteam a few weeks ago, and was accepted. She will begin in the summer. If it all pans out, she should begin competing the new L3 in the Fall of 2014 when she is 6.