text: As idrathernotsay says, we form our most important impression of others in no time at all. \nI'd only like to add that I believe you are mistaken when you think that we know "it's going to work out". We have formed an idea of a person and we treat them a certain way, expecting somthing or other. None of this means that we are right. Our first impression of somebody can be completely wrong (and often is).