It is hard to tell as not every sighting has been recorded, and some are hoaxes, but ever since man has lived on earth there have been UFO sightings. But well recorded sightings go back earlier that the 1600's.
There is no way to know when the first sighting occured. There are pictures on cave walls made by our knuckle-dragging ancestors so it's a pretty safe guess that we have been watched since there has been an 'us'.
1800's ish
1897-04-19Aurora Texas UFO IncidentAurora, TexasUnited StatesAlleged crash of a UFO and confirmed burial of the pilot, purported to be an alien, in the local cemetery.
There is no way to tell when a UFO will be sighted. You have to be in just the right place and the at the right time.
That would be before written history. We can't know who the first person was that saw something flying and couldn't tell what it was.
Wailuku, Maui, HI, and Honolulu also have had many recent UFO sightings.
95% of the UFOs sighted are fake
Seven sightings of UFO's in the US, Canada and France.
UFO sightings have been reported in all 50 states.
There have been many sightings over India, especially in the years 2008 & 2009.
There have been sightings in virtually every continent in the world, India included.
For UFOlogists who study the connection of crop circles and UFO sightings there does seem to be some validity to the theory that they are related in some way. There is a high incident of crop circles the day after a UFO is sighted the night before.
It was first Sighted in 1678 by a French explore.