Most internet sources have dated the first horse-race meeting at The Racecourse as having taken place in 1807, however James Whyte’s History of the British Turf notes that racing first took place at Wrexham 6/7th October 1806.
WREXHAM RACECOURSE.
This is confirmed in The Cambrian Newspaper 18th October 1806
..THE . . , tfisxHfre »? ?|1806-10-18|The Cambrian - Welsh Newspapers Online