Laura, as you know it is very hard to get your first full-time
paid museum job.  Do contact the registrar's office, and if at all
possible try to come up with some available time that is not on
Saturday--some of us work weekends, most do not do so regularly.
I put in my first 6 years in a museum working Tuesday-Saturday,
before I graduated to a Mon.-Fri. job.  Volunteers who do registration
and/or collections management deserve regularstaff contact and should
have someone present who can offer help and guidance.

If you can, you might also offer to help install and take down exhibits.
In small to medium museums. That almost always runs right up until the
opening starts, with the "crew" of curator, registrar, preparator, intern
and volunteers senaking out the back as the guests come in the front.
Having a museum-educted volunteer to help with condition reports really
helped me from time to time.

Good luck, and let us know what happens.