Here are my findings so far -
According to the list of 52 NASCAR races for the 1948 season, Cotton Owens didn't get any wins. His best finish was 2nd at Greensboro Fairgrounds on June 20.
For the 1949 NASCAR Modifiedseason leading up to his June 5 win, here are the dates, tracks, and winners -
Date Track Winner
Jan. 16 Daytona BeachMarshall Teague
Jan. 23 Broward Speedway, Fort Lauderdale Fonty Flock
March 27 North Wilkesboro Speedway Fonty Flock
April 3 Charlotte SpeedwayRed Byron
April 10 Greensboro Fairgrounds Curtis Turner
April 17 Lakeview Speedway Bob Flock
April 18 Winston-Salem Speedway Curtis Turner
April 25 Martinsville SpeedwayFonty Flock
May 1 Occoneechee Speedway Fonty Flock
May 8 Lakewood Speedway Olin Allen
May 15 Charlotte Speedway Red Byron
May 18 Bowman Gray Stadium Fonty Flock
May 22North Wilkesboro Speedway Tim Flock
May 25 Bowman Gray Stadium Joe Eubanks
May 29 Lakeview Speedway Tim Flock
June 1 Bowman Gray StadiumCurtis Turner
(Source - 1950 NASCAR Yearbook)