How many minutes late can I be showing up in the proper room at the courthouse?

I received a jury summons today and was wondering how late I could be before I'd get charged with contempt of court. The courthouse is very complicated, as far as its layout is concerned, and I know that no matter how early I show up, I'm gonna be late, because I won't be able to figure out how to navigate the courthouse to get where I need to be on time.