Multilingual Children

I want a advise, we live in Brazil, and of course, all the other people talk to him in Portuguese. I only talk to my son in English (isn´t my native language) ,
he has 1 year and 7 months, but don´t speak very well. Now i call to a English course and they said who can get him in a a class of 3 children,
now i don´t no what i do, because i think it is good for him to stay with other children and a person who speaks, without me.
Anyway i think ” i´ll be spending my money?” now, in time when i stay with him at home, he knows everything what i say,
so i stay teaching at home or get in a class? what can i do?

Thanks

Danielle Ferreira