Based on the style and the typeface, I'd guess mid to late 1930's.
This pattern offers a sporty, slip-over, short-sleeved version with an attached collar as well as a standard long-sleeved, coat closing style, which can be made up with a detachable collar. Of course, when you make shirts yourself, you have the wherewithal to make up extra collars and cuffs. I know I'd have to make myself do this when I was constructing the shirt, because otherwise it's sort of fiddly work to track down the pattern and the fabric and the interfacing and just make up a collar and cuffs, and the gentleman would be short a shirt in his weekly allotment the entire time I was trying to get this organized.
The trick would be to remember where I'd stashed the extras once I'd made them. If you have the extra collar and cuffs on hand, it's relatively quick to remove the worn ones and replace them.
And then there are the extra cards of buttons to keep on hand. Here's a lovely card of shirt buttons. Pipe-smoking was apparently obligatory for gentlemen wearing dress shirts. Note the nice stiff breeze for both sailing and fluttering neck ties in a jaunty manner.
I haven't made up this shirt pattern. I've made up some New York patterns for women's clothes, however, and the quality of the drafting is mediocre. The instructions are lovely, though.
Originally posted 10/20/2009; re-posted on 3/12/2010 with additional graphics.