Itsycal is a tiny calendar for your Mac's menu bar.
If you want, it will display your appointments and serve as a companion to the Mac Calendar app.
You can move Itsycal in the menu bar just like the built-in Apple menu extras by holding down the command key and dragging.
|To change the first day of the week:
System Preferences... > Language & Region > First day of week
|left/right arrows or H/L||previous/next month|
|up/down arrows or K/J||previous/next year|
|shift+arrows or h,j,k,l||move selection|
|w||toggle calendar weeks|
|command-n||open Calendar app|