Lurker with a pumping question

KrsCrp83

I will be returning to work part time in August when DS is 5.5 months old.  He is EBF and I'm really committed to BFing until he is at least a year old.  I will be working every other day from 7:30 to 3:30 (I'm a teacher) and am trying to figure out pumping times during the day.

How long, including setup and tear down, does a pumping session take?  I will be using a Medela PISA but don't have it yet, otherwise I would just pump and time it.  DS can fully empty my breast in about 15 minutes, but I know that pumping won't necessarily take the same amount of time.

Any info you can offer would be much appreciated!

Thanks!