Probably about half an hour for most kids... However, some kids cry longer.. Some cry shorter.. Some might not even cry.. Once they get used to the teachers and environment then the crying would stop.
Depends, if the teachers are good and experienced, the kids usually stop crying after a few mins(;
My kids didn’t. I think he is more happy to play with his classmate than seeing me. Lol!
My kid cried about half hour and then calmed down