I did not teach my children. I started to after my son went to speech therapy when he was 2 or 2 1/2. I however have started a daycare and I have a group of children between 18 and 24 months and we use it all the time. It is a great resource to keep their frustration levels down from not being understood with their developing language. I wish I had done it with my own children more than I did.
I have taken care of a Down's boy and a hearing impaired boy which is where I got started more. I know there is a class in town because the hearing impaired boys family was taking it. I have also seen a class offerd by the Kent County 4C program but you would need to look on their web site to find out when and where it is. I'm sure that they allow parents to join in and it isn't just for day care providers.
Kudos for learning a new language to work with your child. They will only benefit from it.
L.