A long way....
When can you say you know enough to be safe in the cockpit?
When you master the SOPs....to the point where you practice them
even when distracted, when there is an 'abnormal', when you're tired,
when you're flying with someone who doesn't practice the SOPs, or,
worse yet, has contempt for them.
When the SOPs become natural, normal, the only way....i.e.
you don't how to and cannot fly any other way, other than by
the SOPs.....
Then, you can say you're safe in the cockpit....