Although the overlock machine (aka serger) was developed during the 1870s, it’s difficult to find examples of its use in extant clothing predating the 1930s. The overlock machine creates thread loops for the needle to pass through, binding the edge of a seam. Developed as a method for finishing off the tops of socks and other knitwear, the machine is also used for sewing with small seam allowances.
The overlock stitching machine was invented by the Merrow Machine Company of Hartford, Connecticut, and patented in 1889. Another firm, Wilcox & Gibbs, challenged that claim, but lost their case in court in 1905. Although in use commercially since 1893, the Merrow Machine Company produced an “A Class” serging machine in 1932, which explains why serging became a standard method of garment construction in the ready-to-wear fashion industry at that time.
This 1909 dress is the earliest example I have found to date of overlock stitching. Using a serger in this case makes sense as the best method to sew the delicate, lace-inserted translucent fabric to have the least visible seams.