I wasn’t able to find a step-by-step guide on initiating a wire, but this entry from the Flux Reference may help once you’re in wiring mode:
“While in wiring mode, you can also change the wire angle (elbow) direction of the route by pressing the “f” key. To cancel the routing mode, press the escape key.”
You can read the full “Positioning and wiring” section for more details on drawing and manipulating wires in your schematic.