Reid Hoffman angel investor, Co-Founder & Executive Chairman LinkedIn and Partner Greylock & Ben Casnocha entrepreneur
“Plan A is what you’re doing right now.  Within a Plan A you make minor adjustments as you learn; you iterate regularly.”
“ [Should] you decide you need to make a bigger change, that’s when you pivot to Plan B.  It’s changing direction or changing your path to get somewhere based on what you’ve learned along the way.”
“How do you know when to pivot from Plan A  to a Plan B?  You’ll rarely know for sure when to pivot or when to persist in what you’re doing. In general, a lesson from the technology industry is that it’s better to be in front of a big change than to be behind it. But the question of when to shift exactly is a question of both art and science, intuitive judgment combined with the best feedback or data you can collect . [Expect] both good luck and bad luck along the way that will open and close unexpected windows of opportunity.
The common presumption is that you shift to Plan B when something isn’t working. That’s frequently the case but not always. What you’re doing now doesn’t have to be failing for it to make sense to shift.  If you find that the grass really is greener somewhere else, go there!” Reid Hoffman & Ben Casnocha, book The Start-up of You, pg 58, 68, 70-71