The crowded headstock is a result of an assumption... (snip!)
tbh the "pointy nipple on the upper horn" was more me being lazy with photoshop. I never intended to include that detail.
For a fresh design, you'll save a lot of time and potentially money if you wait for the hardware to arrive then create a 1/4" hardboard prototype. To my mind, there's nothing quite like holding a new shape on your knee to see if it's playable or attractive, and the process will definitely avoid any layout issues that come from designing as you go (such as the dreaded "But I wasn't nearly this fat when I designed it" syndrome.) Also, if you do it well, you end up with workable pieces that can be used for reproducible template routing.
I've never used Photoshop for project design, though - only to make humiliating pics of co-workers. I use TurboCAD to size and layout, since it's fairly precise, and I print to 100% size, so I can trace the layouts directly on to templates. It's a pretty easy and very reliable process. I know others who use SketchUp or other programs for the same purpose. The idea, though, is always the same - to work out the most difficult stuff in the cheapest media. Don't cut a piece of wood until you've finalized the design.
This is analogous to long standing schools of sofware design, and there are counter-arguments. And, frankly, part of the fun is to work through some of this stuff in your hands, not on a computer. But fine wood is becoming a rare and expensive element, and we owe it to our brethren to treat it with respect (Well, ok, hack up all the poplar your want. I can't stand that stuff.)
So, lay it out as accurately as you can on the computer, fine tune it in super-cheap hardboard, then buy and shape your lumber. That's my recommendation.