According to Official Guinness Records,
The earliest monster truck backflip successfully performed in a scored competition was accomplished by Cam McQueen (Canada) at the Jacksonville Monster Jam in Jacksonville, Florida, USA on 27 February 2010.
The Monster Jam series is a motorsport event tour series whose season traditionally runs from January to March. It is sanctioned by the United States Hot Rod Association (USA), with the Monster Jam World Finals held each year in Las Vegas, Nevada, USA. Champions have been crowned in the "Racing" and "Freestyle" disciplines each year since 2000.
For a complete list of 2010 records, please visit 2010 Guinness Records in United States.