Are the beacons capable of an experience like that?
Beacons themselves are only broadcasting their packets every now and then (:
How quickly the receiver detects and responds to these packets is up to the receiver itself. For iOS, in the foreground, it should pick the beacon signal up immediately. When the smartphone is locked for an extended period of time, the time to detect the beacon and wake the phone up and process the action in the background increases.
There's an option called notifyEntryStateOnDisplay in CLBeaconRegion which when set to true, will force the iOS to deliver a
didDetermineState call to the beacon manager's delegate when the display lights up. The state can be either "outside" or "inside" range. So for maximum reliability when checking in, you could ask people to simply tap their home button in order to wake the screen and deliver the state.
Only reads when very close
Setting the broadcasting power to the minimum value of -40 dBm should do that.