pretty sure you can just turn it by hand... those are simple increment-by-one-day calendar date indicators. you'd have to manually adjust if/when there's a 30-day month, so just go for it.... probably want to grab it closer to where it's attached so as to not bend the hand... somewhere in the middle should be ok.
In the calendar mechanism, a pin drives a 31 tooth wheel. This should be set up so that the pin engages the wheel sometime after midnight. That means you should be able to do what Bruce says. If you feel some resistance, the pin may be engaged with the teeth. Wait a couple of hours and then try again. You will have to make adjustments after any month that does not have 31 days.
If you want instructions to set up the clock so that the date change is just after midnight, ask that question and we can help you with that.
As you rotate the calendar hand, you should hear and feel the hand clicking/jumping at the day marks. If not, the hand is slipping on its shaft. Not a big deal but it will eventually need to be
tightened. Willie X