Manually start Time Machine backup without menu bar icon
If you'd prefer not to have or use Time Machine from its icon on the menu bar, it can be started/stopped, and more, via Terminal, e.g.:

tmutil startbackup


Or:

tmutil stopbackup


The startbackup verb also can take options, i.e:

tmutil startbackup [-a | --auto] [-b | --block] [-r | --rotation] [-d | --destination dest_id]


Have a look at its manual page: man tmutil