Hi, Olenka!
My youngest has been able to name, meaning SOUND the notes using Soft Mozart since he was 1 year old
And he had access to the keyboard (that has the SM symbols on it) after he was 6, there is even a video of us with him pressing the keys at 8 months.
I would use Soft Mozart just like Little Musician - as early as possible. For the younger kids, babies that is , I would play to them as parent, learning myself, actually that is what I did. We played with the Soft Mozart cards all day long, we had a home made book with the cards, and I allowed each of them to play with Guess Key game. I suspect the youngest knew the notes before he could speak. Cause they were among the first words he spoke at that age (maybe the first words too bwah ha ha).
Seriously, just dare. That's all it takes (beside money to buy the software) - you just do it and set and example, play games and give them a music environment. Both Brillkids and Hellene are right - kids CAN learn very early. Hellene said 2 years old as the earliest age but I think, just like our case shows, that one can use it even much earlier.
It's much easier and more fun when you have older kids playing with stuff, the youngest just soaks in everything.
You should see a 3 year old playing the keyboard - he stole finger positions from his older brother and his mom and maybe even from the videos he watched over time. When people see our kids they say they are geniuses or gifted. I'm convinced they both have a potential that has been helped to get out to light.
Andrea