You can create a shortcut for a backup task and start the backup task by double-clicking on the shortcut on the desktop.
Navigate to C:\Program Files (x86)\Acronis\TrueImageHome\TrueImageLauncher.exe (or C:\Program Files\Acronis\TrueImageHome\TrueImageLauncher.exe)
Right-click on the TrueImageLauncher.exe and select Create shortcut, move the shortcut to the desktop.
Right-click on the shortcut.
In the Target field add /script:XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX (make sure to leave a space between .exe" and /script) where XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX is the ID of the backup task you can find in C:\ProgramData\Acronis\TrueImageHome\Scripts (if there are several tasks, right-click on a task and open it in the Notepad to see the name of the corresponding task between <display></display> tags)