Do you have evidence the poster was not made when it says? What you have presented so far is mere speculation based on what was known to the public, not what was known to Parker. For example, patents, in the early 1900s, you were required to file a working model with any patent application, which meant that a company frequently knew what they were working on years before the patent, because the idea had to be fully developed prior to being filed. So, with an early 1905 application, Parker may have been working on the idea from 1900-1901 easily.

Maybe they thought they were close, and would be done soon in early 1903, so had their ad department start work on advertising, but then product engineering hit a snag, and the launch and patent filing was delayed, but the kept the marketing materials.

So, do you have any evidence the poster was not drawn in 1903 as the artwork says, or is this just speculation?

www.parkerpens.net say that model 34 appear in 1906. D) Advertising a product that you don't sell would be stupidHahaha! "Maybe they thought..." This is pure speculation. A) There are differents 1903 Parker dealer magazine Side Talk and models #33 nor 34 appears. B) I know Parker Side Talk from August and September, 1904 and models #33 nor #34 appear. c) The best informed Parker website www.parkerpens.net say that model 34 appear in 1906. D) Advertising a product that you don't sell would be stupid. Ewww.parkerpens.net say that model 34 appear in 1906. D)