I would say that muscle requires weight gain, so maybe gain muscle first and gain the weight necessary for that, and when you're happy with your muscles, you can lose the excess weight. That's just my opinion though. Both options work. It eventually boils down to a personal prefrence.

I would probably say that weight loss comes first and building muscle after, but this is just my personal preference. Because muscle weighs more than fat, it's better to start at a place where you know that your happy and healthy and any extra weight is muscle gained, but you could do it the other way round too. Any way that makes you feel comfortable really, while building muscle you also lose a bit of fat as well so... but i would say weight loss then muscle gain.