Hi WW!
The travel component of the DIS is done either over January intercession or in May. Academic work is actually begun the preceding semester.
As I've posted before, this is a great program. The cost covers pretty much everything including 4 credits. However, on the downside, Drew has just been forced to increase that cost quite a bit because of transportation increases and other factors ($2960 for first-timers next year). Given some of the destinations (Egypt, Buenos Aires, China, etc), it's probably still a good deal.
Here's a link to their web page:
Drew International Seminar (DIS) Program