The Four-Second Rule
Acknowledge every within 4 seconds of the door opening.
Within 4 seconds of a crossing the threshold, you must acknowledge them. Lift your head. Eye contact. Smile. One-word greeting (Hi. Hey. Welcome.). That is acknowledgment. The rest of the greeting comes when they reach the counter at 6 seconds. Why 4 not 10: 10 seconds feels like an eternity to someone standing in a doorway. 4 seconds is the difference between welcomed and ignored. Walk into any fine dining room: the host's eyes meet yours before the door fully closes. We hold the same standard at a fast casual counter.
What the four-second rule is not: it is not yelling welcome from across the room. It is not waving at someone with both hands full. It is not a fake corporate-trained singsong. It is a real, calm, sincere acknowledgment that you saw them. Even if you are mid-order with another , you can lift your head, make eye contact, smile, and say one word.
If you are mid-transaction and a new walks in: lift your head, lock eyes for half a second, nod, say hi or one moment. The guest in front of you understands. The guest who walked in feels seen. Both are happy.