Bluemagic I see your point about electric, but my little guy has not had any problems with his electric and he's quite proficient with it at 6 1/2. The cool thing with an electric at this age, and younger, is they can experiment with the sound. Throw in a pedal and some feedback with an amp and they are hooked.
My son wanted to play The Avett Brothers on guitar at 4. We open tuned his electric and he could strum and sing to any of their songs. Very happy guy. We have a lot of guitars at our house. Classical, acoustic and electric. If we had forced him to try classical he wouldn't have loved it and would have stopped playing. It totally depends on your kid. If we had listened to everyone else we would have waited for piano until after 6. We started at 5 and he's already at an intermediate level loving Bach and Mozart. Go with whatever they want to do at 2.7 and you'll have a happy kid. Oh, and hand drums are also a must. We have bongos, a djembe, shakers, tambourines, make your own instruments!
Experiment and have fun! Can you tell we love music at our house?
