A Collectors Weekly post tells the story:
“As Shwayder’s brothers joined him in his enterprise, the company issued a line of luggage they dubbed, ‘Samson,’ after the Bible’s famous strongman… Despite the Depression, Shwayder continued to improve upon its more exclusive brand of products, with frames made from real wood, rayon linings, durable handles, secure locks, and a special fiber finish the company developed specifically to cover its suitcases. In 1939, Shwayder introduced the tapered ‘Samsonite’ suitcase that was enveloped with a tough, vulcanized fabric.”
See more at http://www.collectorsweekly.com/bags/suitcases
The U.S. registered trademark notice shown above has a 1938 date. That would be expected as a business would file, and hopefully receive, trademark protection before showing a new name to the trade. It would then take several months before the new item was made known to the public.
A photo of what is described as a 1939 Samsonite suitcase can be seen here: https://www.flickr.com/photos/66114713@N06/6117895872/in/photostream/ .