There's a new Time Machine menu in the Menu Bar:

The new Time Machine menu bar menu has a "Back Up Now" option, however, they did not add a backup now button to the System Preferences Pane for Time Machine. So if you uncheck the "Show Time Machine status in the menu bar" option, you can't start a "Back Up Now".

See attached image for full size.
Able
Comments
TM icon in the Dock can do that
Right (or Ctrl-) click on the Time Machine icon in the dock. There is an option to backup now.
Thanks for the feedback
I don't keep the icon in the dock, but it's good to know for those who do. I wonder if you could always do that or was that added when they added it to the menu?
Able