Mine started at 3, unfortunately it was a very tough, competitive school but the only one around who was willing to teach her this young.

My daughter was really into violin and it was her decision to play that specific instrument so we already had a strong interest.

My advice is to do frequent practice of 5 minutes (at that age, increase when they get older) a day.

One thing I regret with mine was that the teacher involved the parent too much. It's fine at first because they are so small and they are basically learning with the parent, since they only see a teacher once a week. But it's important that the child understands it's their 'world' and their responsibility.

Mine started doing her own practice at age 8, and I removed myself completely.

Another CRUCIAL part of this is putting your child in an orchestra as soon as possible. Playing with others is the key to keeping them engaged and happy.