Good morning everyone.
I had a think about and a look at the colour changing in Gerald while I was making a second sock last night @Phoenix_Rising. I think the way you have done it looks exactly the same as the way mine do. I can't see where that is wonky though it puzzled me for a moment at first glance
I took these to show you what my colour changes look like. I'm using two strands here so it looks a bit different on the hook, but it works with the same idea as one. This is all single crochet also.
This is what it looks like with one loop pulled up and through (the first half of a SC stitch) as my last rainbow stitch.
This is catching the next colour ready to yarn over and pull through both loops to complete the stitch.
This is what it looks like as a completed stitch.
This is the first stitch in the new colour.
And this is after four stitches.
I can see that my first stitch in the new colour is a tiny teeny bit bigger (as per the second last photo). I leave it kind of loose until I have finished a few stitches and then I tighten and adjust the stitch from the tails at the back, before snipping them and tying them off.
Once I've been around more times, it looks very similar to Gerald's leg. If anything, my first stitch is slightly smaller as I pulled it too tight.
The only suggestion I have about colour changes, would be to try to make them where they're least visible. In the socks I put them underneath, as an example. You may need to change colour earlier than the pattern suggests but as long as your stitch count is what the pattern requires, it doesn't matter.
When I zoomed in on his leg, my face did this 😮. Your tension and stitch sizes are incredible. So impressive!
Re hooks and sizes in my wing it world, I choose what hook works best for me based on my crocheting style. If you're using the same yarn for Baby Dragon as you did for Gerald and you're happy with the way that worked (it wasn't too tight to get your hook through the loops, you were able to catch the yarn without needing to try too hard, it didn't split the yarn too often etc.), then I'd use the same hook. In saying that, wing-it style isn't for everyone and I think @Former-Member has a much better idea about technicalities, and might come along with some better advice
I hope your baby dragon making helps with operation stay alive. I'll be around-ish if you have any hiccups and want to ask anything, though I have a sneaking suspicion you've totally got this ☺
Crafting feel goods sent to all who may like them today ❤
(Random side note, I'm wearing my favourite pj singlet in the pics above. There's a hole (or six) in it now. Apparently embroidery scissors are very very sharp and it's not a good idea to wear your favourite clothes while snipping at yarn with sharp things 😆)
perhaps not her precise why's, but the concept. 
