Jigs, fixtures, and templates are for production of identical parts in industry.
You can make a great guitar by:
A- cutting to the perimeter line and B sanding to the line as has been done by countless of people before pattern bits became available. This forum is heavy on templates
but that doesn't mean you can't do it other ways too. I made bodies for years and didn't template rout the perimeter. I found it faster and easier to cut and sand myself hence this long winded comment.
If you've read the build threads...you've seen mistakes and perfection in them. With and without templates. You just need to make up your mind on what you think you need to do to make the best body you can given your available resources and experience.
That looks like northern ash...baseball bat stuff.
This is a good thread for you: