not all of your answers but I have seen Dandy pocket bikes from as far back as the 1970s and one of my customers remembers seeing the first pocket bike in the US used at the 1981 Formula One Grand Prix of Detroit, it was used as a pit bike for one of the teams. That is obviously not the first sighting just the first time he saw one and that dates back quite some time so unless someone knows of an earlier time you can use that as one of the first sightings.
