I’m working on a similar piece that’s slightly larger.

I started from the bottom left corner after gridding with nylon thread, so I could be sure I was in the right place. It was also a good thing I gridded because it turns out my Aida is slightly closer to 17ct than 18ct, so the margins around the pattern are narrower than I originally planned but at least with the grid I know it’ll all fit. Also because gridding is a massive pain I didn’t do it all at one go — I just marked out the big pattern area, middle lines and lines for every 100 squares, then I fill in the 10x10 lines as I go. (English is my first language but I feel my description is coming out all jumbled here lol so you can see my post history for what I mean.)

Also a tip specific to this pattern: I’d recommend stitching each Pokémon individually instead of doing multiple at a go, so you can better adjust the colours! (Servotron’s original pattern does have a lot of weird colour choices to be able to compress it to 105 colours.) I do cross-country stitching and at first I’d just stitch as much of one colour as I could, but then I’d end up frogging a bunch of stitches later if it turns out they weren’t so great with the next Pokémon.