How does adding another class work?

[Marlin9276]

Hi, 

Apologies if this is a redundant question but I'm a bit confused on how adding another class works. 

What I do know about it is that you can only have two active classes at a time. But I am able to request a third class after I've submitted a final (I know I can request a fourth if I finish both classes early). So say I finish a class in two weeks, and then I request a third class; for that third class, I have to complete it before the 8 weeks of the term is done, right? So in my example if I have the third class added after the second week of the term, I would only have 6 weeks to finish that third class or else it'll be counted as an F since I didn't finish it within the term.

I appreciate all the help.