At this point does it matter? Trump will not be getting another term. Just wait it out.
And Clinton was supposed to win without any doubts :)
Yes, let's wait it out!
For the OP: never... There is no reason to do that at this point.
Well, a +4 in the polls to a +2 in the election with the electoral college turning was always a possiblity, only some folks like the Huffington Post decided to ignore it.
But the Republicans won the presidential vote a single time after 1988 - Bush Jr. with over 50% approval, and a fairly centrist Republican congress. I'd say there is a very, very low chance Trump gets anywhere close to winning the popular vote.
Electoral college is another matter entirely, of course, and will probably be relatively tight even if the election is won by five points or more.