Navigating by date
You can navigate across days using the 'Navigate' menu.
Using the Calendar widget
You can also left-click any date in the calendar and it will jump to that date in your open tab.
The act of jumping to a new date automatically saves whatever current date you were on, so there is no need to save first.
Tabs
You can also right-click on a date in the calendar and open it in a new tab. If that date is already open in a tab, it will jump to that tab instead.
Jumping to today's date
Use Ctrl+Shift+T to jump back to today.