The choke needs to be open enough for the motor to draw enough air to start up, in most designs I've seen that's "up" on the lever. (In some conditions that may need to be different). Some need to have the choke wide open (up) for the initial start then closed (down) once the motor catches. On the stock "Carb of C'thulu", I've never had to change the choke after the first few starts unless it's cool and damp that day.
In my case when leaving the house, I start off with the choke lever up, start up, do a U-turn, stop and swing the choke lever down, wait for a few seconds for the motor to sound steady, and go. If it's colder and/or damp I'll wait up to a half minute with the engine idling on the first start of the day before I move the choke completely to let it warm up a little bit before I open up and go.