paula,
I do hear of kids starting at 2.5 years... but those are mainly private suzuki violin tutors or lesser known schools. Those bigger ones I know accept at 3-3.5 years old or older.
Learning an instrument requires a lot of discipline and commitment on both child and us, eg. practising rain or shine every day, certain pressure to keep up with class pace. And at our kids' age, they get distracted easily and will shift their interest at times, those are hard times where we need to insist on them practising and yet make it fun and encouraging for them cos that's the spirit of the suzuki method. At least in singapore, learning music is something you will find it easy to give up half way since its not academic and in the sense, you wont die if dun learn kind. But learning a skill or an instrument, once decided, is about commitment and value... so we must also prep ourselves to have the determination to accomplish something out of it before starting so as not to instill the wrong value that its ok to have half past 6 commitment.
Though S loves instruments and had been asking for violin classes since 2plus, I observed him for a period of time and keep asking him for his commitment before we sign up. And even then, I experienced periods of time where he is distracted and wanted to play something else and dun wanna practise his violin. At those times, I struggled a lot ... my response range from coming down very hard on him and reminding him of his commitment and that its his choice, to trying my best to move slower in the practise to encourage him. After a day's work, felt so tired, at times even I myself feel like giving up cos I gotta encourage him and make it a fun time for him, so when he dun cooperate, its really very frustrating.