You are rich in micas!
Your dish soap looks just like mine. I make mine w 95% coconut, 5% castor. Scented w peppermint and litsea.
I think you can mix oxides ahead of time - if you put them into something and cover it. I recommend a cheap dollar store cutting board if you don’t have glass, as long as it’s smooth on one side. If you are using a pallet knife it is tricky to smush the oxides if you can’t get your hand low enough, I.e. if you’re trying to mix them in a container with edges. This probably doesn’t make sense, but once you try it you’ll see what I mean.