When adding a notification for an event, it's only possible to specify the notification time as relative to the event time (X hours in advance, etc.). It would be useful to have another option that allows to specify the notification time as given date&time.

If it's technically difficult to remember the notification time this way, it'd be enough if BC automatically converted it to an offset, so this could be merely a UI addition (another possibility in the list of notification offsets when adding a notification or when postponing it). The calendar application DigiCal has this functionality.

Example use case: I have a language class at 17:00, and I want a notification at 8:15 in order to remember to take with me the textbook before leaving for work. Having to manually calculate that I need to set the reminder as "8 hours 45 minutes" is cumbersome and error-prone.