Expiry dates occurring during an event are pretty unusual, and I wouldn't normally expect to see them occurring on scrolls - but it is clearly possible under certain circumstances (it may be that (some) scrolls created at the Spring Moot last year had expiry dates incorrectly calculated or recorded, or they may be from a non-standard source, for example).

Edit: Correction to account for rule-book definition of a "day"

Anyway, to answer the question - the expiry is deemed to occur at the end of the date listed, at midnight.
i.e. these scrolls are valid for all of the Friday and Saturday of the event, and the 14 hours of time-in on Sunday from 10am until midnight - if still unused at this point they expire.

Anyway, to answer the question - the expiry is deemed to occur at the end of the date listed - which, by the rulebook definition of a "day", is at the 2am time-out (i.e. it includes the first 2 hours - midnight to 2 a.m. - of what is technically the Monday, but we treat as part of the Sunday for rules purposes)
So these scrolls are valid for all of the Friday, Saturday, and Sunday of the event - if still unused at time out on the Sunday, they expire.