The opening of your speech has always been deemed über-important because that's when you have everyone's attention. Audiences also use those first few seconds to decide whether or not to even listen any further.
Now, some researchers are telling us that that the decision is being made even earlier.
It turns out that your "audience" starts deciding all about you as you get up and start moving toward your starting point or podium. People create a first impression about you as their minds place you into the role of "speaker." Then, that impression impacts how they interpret everything you do thereafter.