I get lots of press releases in the course of a week, and few of them catch my eye. However, this one did: A Robert Half International Survey of senior Canadian executives says that it takes 12 minutes, on average, for the executives to form an opinion about a job seeker they are interviewing.

Maybe things are different north of the border, but 12 minutes to size up a person is wildly out of whack. I’ve personally interviewed thousands of job candidates over the years and if there is one thing I have learned, it’s this: You know if you want to hire someone in the first two minutes of talking to them.

I could write a book about this, but the old adage is definitely true: You only get one chance to make a first impression. For job candidates, this is crucial. Executives and hiring managers form opinions quickly and it is difficult to change them once the initial impression has set in. Yes, I’ve had candidates who “warmed up” during the interview and ultimately made a favorable impression on me, but that’s the exception and not the rule. For the most part, my first, gut-level impression was right on the money.

I’ve also learned over the years to place my trust in this first impression, even if I don’t know exactly why I feel the way I do. Malcolm Gladwell wrote about this in his book Blink, about how “we think without thinking about choices that seem to be made in an instant—in the blink of an eye—that actually aren’t as simple as they seem.” Managers who do a lot of interviewing know what I’m talking about. You size up job candidates quickly and develop a strong impression on the fly. Whether you work in Canada, where it takes 12 minutes, or down here in the States, where we jump to conclusions more rapidly, the message to job candidates is clear: You must sell yourself quickly, or not at all.