c. 1610
The Judgment of Midas, a painting by Flemish artist Adriaen van Stalbemt, includes a trombone. As in numerous Flemish paintings, the trombone rests on the ground rather than being played (see below image; public domain). 
The Judgment of Midas, a painting by Flemish artist Adriaen van Stalbemt, includes a trombone. As in numerous Flemish paintings, the trombone rests on the ground rather than being played (see below image; public domain).