How long will my boyfriend be in jail?

My boyfriend sent me a text Sunday morning saying “sorry I didn’t hit you up, I’m going to jail right now”. I didnt worry at all about it because I knew it was for something small. His friends posted his mug shot and I found out he went in for not going to school five years ago… He graduated at the age of 17 and he’s 21 now. I don’t see why they didn’t just give him a court date I’m sure the judge will drop the truancy charges but how much time do you think he'll serve or atleast how long should it take for him to see a judge? I assumed he’d be out or see a judge the next day.