Congrats on your order and welcome! You’re coming in at an exciting time and can learn along with the rest of us. Things are really ramping up as folks are getting their machines so there should be an explosion of new info getting posted. I’ve received my golden ticket (delivery email 
), but it’s a few weeks before delivery so I can’t speak from direct experience yet. We seems to have a very similar background. I’m pretty proficient in photography and various graphics arts with a good background in vector and raster programs, but I have little (none) experience with 3D stuff.
There have been a few looks at the GF UI (user interface) though and it seems to be pretty basic and not requiring a lot of experience to get familiar with it. (People are able to scan/trace and get cutting within minutes of getting their machines.) All the detailed prep work seems to happen in graphic and photo editing software like you’ve mentioned and with a 3rd party 3D modeling software. Becoming more proficient with the 3D and vector programs might be your best bet.
Here’s a good place to get started along with lots of searches and reading on the forum.