Does the MOB need to get dress before MOG?

I think back when the bride's parents hosted, it was proper etiquette to let the MOB choose her dress first. Obviously times have changed and I personally wouldn't care if the MOG purchased her gown before me.

We did not coordinate at all. I told them how dressy the event is and what our colors are (for info only) and told them to pick something they feel good in. My mom got a gown in the colors of our wedding and dad got a suit in our colors. No idea what FMIL is wearing. I'll see at the wedding.

I feel you, OP. My FMIL is insisting that my mom get her dress before she goes and shops. My mom is really laid back and probably won't go get a dress for a few more months (which I'm totally ok with). I've told FMIL multiple times to just go choose a dress and wear what she wants, but she won't. I'm at a loss at this point now. Can't force my mom to go get her dress, and can't convince FMIL to go get one either.

Ug I feel you. My mom insisted on coordinating with my FMIL. Luckily my mom is a super plan early kinda person so she chose but hadn't paid for it until she consulting FMIL and they agreed. Both are wearing black now (so are my BMs). Good luck, my only advice is even if your mom doesn't want to shop so early, if it matters to your FMIL then she at least needs to agree on color choices early.

Maybe you could choose like 5 dresses online that you like style and color wise and send them to your FMIL to give her some guidance. Even though it doesn't actually matter to you what she wears, it seems like it matters to her that you are involved in some way.

I don't see the reason to have MOB pick first. Tell her to do whatever she pleases, send you a pic of the dress she gets and just tell your mom not to buy the same exact dress.