I think parents are more worried about their child's first day than the child is. I was like you and your wife when it came to the first day, would they make friends, would they cry and miss me, would they want to go back, I remember these things and they all turned out to be nothing to worry about, they made friends and liked school.
I am sure your son will make friends, it might take a few days but he will make them and find that he likes going to school, give him time, and the two of you, to adjust to it.
It is good that they teach two languages, here the schools offer Spanish and English to the younger children, in higher classes they can choose a language they want to learn.