Not really sure on this one. I am pretty new to this sport. I would like to say it depends on the child. I know that I take this whole gymnastics life day by day, LOL, but I think it really depends on the kid.
My DD started gymnastics at age 3 1/2. She had been developmentally delayed at birth, but with PT, OT and mommy therapy she became almost the complete opposite & was super strong. She used to run full speed doing a front handspring in my house or grab my hands and climb up my waist to flip over. I am sure everyone on this board is nodding right now that their DD's did the same thing! We signed her up after watching a class w/a friend. She was in rec classes from 3 1/2 to age 5. 45 min or an hour was never enough for her, she always wanted MORE. Right before 5 she got really bored and I almsot took her out for another sports program, but on her 5th B-Day they moved her up to Pre-team. We thought the 4 hrs a week would do her in and she would be done. She never complained and loved the extra time. She could have gone to team earlier but we waitted until the 6th B-day. When the hrs increased again to 10.5 hrs/week, I thought she would be done. All along she did other activities like Girl Scouts, CCD and T-Ball too. We are on yr 2 getting ready to compete again. I would love to "hold" her here as far as the hours. I am afraid of burn-out when she gets to the next level & hours will increase again. But for now she still loves it and aspires to be on the TOPS team. She's only 7 and I know her interest could change at any time and we try not to get too far ahead of ourselves. In Jan we can re-evaluate if she wants to move up and take on the extra time, she will be almost 8 then. I never want to look back and think I made any mistakes or that she missed something by doing gymnastics. But to answer the question finally....I think this was the right age to start gymnastics for her because she is such a physical child. When she is not in the gym she is bored and bouncing off the walls. I tend to think if it wasn't gymnastics, it would have been another sport for sure because she's been like this since birth. She did dive team over the summer and wanted to do Winter dive but with 3 kids it is too expensive and too much of a time comitment. I don't see her going to the elite level in gymnastics, I don't even think about getting to L5 yet. Right now she just loves it, and loves being in the gym and loves conditioning and being strong.
The only concerns I would have about starting at the early ages is for those parents that get sucked in & try to push their children thru the levels. They think they have to start early to get their kid to the Olympics! They want their children to get more privates, more practice time, open gyms, more time period! They are thinking more time means better. Couple girls on DD's team go to the gym in the morning before school for extra time training for HOPES, get privates and go to practice...sometimes they are in the gym almost 6hrs on some days already. CRAZY! I think age doesn't matter as long as you child is in it 100% and you know how to use your judgement.