Hey Sunnydays ... do the parents insist you speak to the child in french ? Coz kids will learn fast and they will learn by watching the others speak as well so he will immitate them., If it was me, I would want my child to learn a second language as well. So, just use the terms you are comfortable with...he'll get it after a few repetition.
By the way if you find a good way to get him to say please and thanks (eng and french non matter) ...let me know coz I have this 2 year old who refuses to say it... he's they only one after 2months still will not say it.