Modeling time intervals

Hi,
I am looking into expanding the reporting capabilities for our organization
by doing a data warehouse and using analysis services cubes. I am fairly new
to these concepts but have a solid understanding of OLTP databases. The
first issue I want to tackle is how to model time intervals. The final
results will be a hierarchy of time across the x-axis with fiscal year,
fiscal quarter, month, the y-axis will be a hierarchy of agency, program.
The measure will be enrollments. I see the follow dimension tables; time,
agency, program, client. For the fact tables will I have one that would have
both enrollment and exits, or will this be two different tables? How can I
then set up the cube to get me this measure?

I would think this type of problem is not new and many recourses would be
available for me, but I guess I don’t know the proper language to find the
results online.

Any help, or direction to an existing article would be appreciated.