Currently the clock counts "days", "hours" and "minutes" of Game Time. - eg, it is Day 4.
This does not really work that well for simulating time travel, in my opinion.
Assume the party travels into the future. Day 4 changes to Day 24. But that suggests it is the party's 24th day of questing. In fact, it is only the party's 4th day of questing.
For the concept of time travel to work there really needs to be an objective standard of time that is not fixed by reference to the party (ie, a calendar -- ideally, configurable by the designer in terms of Month names, number of months, number of days in each month). Because the party will have been adventuring for only 4 days (it is still Day 4 for them) but the calendar has moved on 20 more days.