As I have written here before, the invisible primary includes a phenomenon referred to as the “Cinderella cycle.” That is, at any given time, a contender, for some inexplicable reason, is in possession of the proverbial slipper, and so rides a wave of positive coverage and rampant speculation — but then he or she eventually finds the slipper doesn’t fit, and a new contestant picks it up to try it on. During a candidate’s time as Cinderella, the media coverage and accompanying good poll numbers make him or her look like the probable nominee for the party and maybe even like a potential president. I remember the positive portrayal of then-Texas Gov. Rick Perry four years ago and Mayor Rudy Giuliani eight years ago and all the matter-of-fact accounts of how they could be the Republican nominee in 2012 and 2008, respectively. Simply put, it’s not wise to take today’s headlines and extrapolate out to the next election. It’s way too early.

So is Donald Trump something different, or is he just having a good run with the slipper? As we emerge from the summer doldrums and Labor Day, there is already some speculation that Ben Carson and Carly Fiorina are on the rise. Maybe they are. But maybe Trump fatigue is setting in with some in the media and the Republican activists who really follow the primaries, and the slipper is looking for someone new.

For no particular reason, I think at least three candidates will hold the slipper between now and December. December is when votes will really begin to coalesce in Iowa. And the trick to winning Iowa won’t be anything new. I think it was Rich Bond, President George H.W. Bush’s 1980 Iowa coordinator, who said the way you win Iowa is to “organize, organize, organize — and get hot at the end.” Of course, no one knows who is going to get hot at the end. It’s almost never true that the person who is hot in September is the same person who is hot come caucus time. And, while we are looking ahead, it is also true that New Hampshire voters almost never confirm Iowa results. So remember that winning Iowa is not the big win that all the media coverage suggests it is.

But then how can we really critique a candidate’s performance in the months before voting begins? Look at the candidate’s cash-on-hand, figure out what you can about his or her Iowa organization and gauge how much he or she will be able to spend in New Hampshire and South Carolina. That will give you a pretty good sense of how the candidate will do in the long run.

By my reckoning — again, with no particular scientific insight — only about 5 percent of what matters in Election 2016 has already occurred. The corollary of that is that 95 percent of what matters hasn’t occurred yet. So if a candidate is doing particularly well or particularly poorly, he or she is doing so within that first 5 percent. A candidate has a lot of room to improve his or her position, and a lot of time for things to go wrong. You can’t believe that today’s polls suggest the eventual outcome of the primaries, nor can you look at any negative coverage from today and declare, “Candidacy dead.”

Scott Walker, who is currently in the dunking booth as the “candidate who isn’t meeting expectations” du jour, can take heart.

Meanwhile, in the Democrats’ race, Hillary Clinton can take heart as well. Even though her campaign is looking more like Queen Mother Cersei’s walk of atonement from “Game of Thrones” rather than the regal stroll she wanted on her way to the Democratic nomination, she is still the heavy favorite to be her party’s nominee. Things may get better for Clinton. It’s my bet that Vice President Joe Biden doesn’t run. And Obama’s Justice Department can be counted on to slow-walk any inquiry that could really hurt Clinton. But she is still vulnerable to what congressional investigators find and will certainly be vulnerable if her former or current staff members decide they need to protect themselves from prosecution by blaming others. Only a Clinton could be in a situation where the realistic possibilities for the next year include both a criminal indictment and clinching the nomination to be president — and really, one may ward off the other from occurring. Anyway, the bottom line is that it is still early in the race. And I remind everyone that in American politics, what is supposed to happen tends to happen. At this point, nobody has lost his or her party’s nomination — and nobody has won it, either.