Finished my first schematic after two weeks of evenings

Congrats on getting there, seriously. My first finished board was a controller for a chicken coop door, and I made almost the same mistakes you did. Mine had no decoupling anywhere and I tied a config pin low that shold have been left alone, so the thing booted into a test mode I didn't know existed. Took me a week of head scratching before I went back and read the datasheet properly, which is now the first thing I do instead of the last.

On the layout side, one thing that saved me was printing the footprint layer at actual size on paper first. I dropped my connectors and the programming header right on top of it and realized my programming cable would have blocked the enclosure lid. Ten minutes with paper and scissors beats a respin every time. Also, label everything in silkscreen while you still remember what each test point does. My second board had three unlabeled pads and future me had no idea what they were for. Your valve driver will probaly switch something inductive, so if you haven't already, check wheather there's a diode needed across that output. Ask me how I know.

Two weeks of evening drawing is about my pace too, so you're not slow.

Funny, my experiance was the reverse. The schematic felt like guesswork but the layout turned out to be the part I actually enjoyed. Once I stopped trying to make everything pretty and just let the traces go where they wanted, it clicked. My first board was a thermostat for my garage heater and I laid it out like a puzzle, everything packed tight, and then spent an hour with the soldering iron cursing myself because two pads were too close togather for my cheap iron to work between. One thing that saved me on that build: I printed the layout at actual size on paper and stuck the real connectors and the programming cable on top of it. Found out my USB plug blocked the header before I ever sent the files off. Cost me one sheet of paper instead of one board revision.

Also, don't feel like rev 1 has to be perfect. Mine came back with a swapped pair on the sensor connector and I just cut two traces and jumpered them with wire. Ugly, but it ran for a whole winter before I spun rev 2. If your garden board comes back with one dumb mistake, that's still a win in my book. Keep the parts big and the pins spaced out on this first one, you can get fancy on the next go around.

The bit about moving connectors early is real. I did my first layout without thinking about where the wires would physically come in, then had a connector pointing at the middle of the board where nothing coud reach it. Had to live with a loop of wire for months. One thing that helped me before layout: walk away from the schematic for a couple days, then look at it fresh. I caught two swapped nets that way. Also run whatever ERC check your software has, it's annoying but it'll flag floating pins you forgot about.

When you get to footprints, double check the part number on the footprint matches the exact chip you're ordering. I once picked a footprint for the wrong package variant of the same micro and didn't notice until the boards showed up. Soldered fine, talked to nothing. Also throw a revision number and date somewhere on the silkscreen so when board 2.0 comes back you know which one you're holding.

Update: the story about the connector pointing at the middle of the board made me go back and sketch where the wires will actually come in before I place anything. Also took the advice about checking the footprint against the exact chip I'm ordering, and sure enough there are two package variants for the micro I picked. Glad that got mentioned before I ordered boards.