Regarding music: We started lessons in piano at age 4 (traditional and not suzuki). It was hard for me to find someone who taught traditional piano for children at that age.
Before that, for my very musical son, we enrolled him in a very good play based developmental pre-k and preschool program 5 days a week. They had daily singing, circle time, dancing to music, music at naptime, sing-alongs with music instuments etc. I also bought him a cheap keyboard and taught him things like Twinkle Twinkle and Old Macdonald (I just googled for these songs as I don't know music). 4 was a great age to start music, in retrospect. My child is a hard worker and he is very eager to learn and is an extremely compliant and musically inclined student. But, he would have had a hard time with the practice requirements if he started earlier than that. And with instruments, practicing is essential to progress. Otherwise the child might get frustrated and want to quit. And be aware that at the early ages, the music teacher might expect you, the parent to be available at every lesson to take notes and learn with your child so that you can go home and help with the daily practice sessions. You need to be with your child while he practices (in our case, our teacher expects my help at home until DS is 8 years old). So, that is a long term time commitment for the parent.
I recommend that you wait until your child is atleast 3.5 years if you want to enroll him in formal music lessons. Piano is a lot easier for very young kids to learn than violin from what I see at our music school. And until then, keep the music exposure constant.
Good luck.
