People notice far more in the first few minutes than they could ever articulate, but the observations cluster into three streams. Surroundings come first because they are visible from a distance: cleanliness, order, lighting, signage and how easy it is to know where to go. A space that answers the question what do I do now without anyone asking has already made a good impression.
Communication is the third stream and the most remembered: tone of the first greeting, whether the person was expected, whether instructions are clear and given once rather than corrected repeatedly. Small frictions weigh heavily here, a name misspelled, a promise from the booking not honored, being passed between people.
The underrated element is congruence. When the website, the physical space and the people all tell the same story, trust forms quickly; when they contradict each other, polished promises but a chaotic reception, the negative signal dominates. First impressions are really a fast audit of whether a place is what it claimed to be.