We made the decision to reduce exposure to English in our kids' early years so they would learn to speak our language (Tamil) first. (We aren't concerned with them reading or writing in Tamil - just speaking and understanding it.)

My first son is almost 3 and I'm wondering if we should be switching to English at home soon since he will be going to kindergarten at age 4.

He currently speaks Tamil very well, and knows the English alphabet, English numbers up to almost 50, all the basic colours and shapes in English, and some random words and phrases as well.

English sentences, however, frustrate him because we try not to speak to him in full sentences. Should I be doing that starting soon, or let him learn at school?

Also, our plan is for him to switch to French immersion as well (I think it starts in grade 1 here), so that would factor in as well.