I think I'd lean towards FAR for three reasons. It has the most material, so having extra time to study for it (at least now till January) would be a good thing. For a lot of people, this one gives them the most trouble, so having it out of the way when your 18-month timer starts would be a good thing! And…since AUD is basically about enforcing the rules, and FAR is basically about learning the rules, it makes sense to take FAR first so that you know you're familiar with the rules, cause it's hard to enforce rules when you don't know them to begin with. 😉
But, those aren't absolute reasons to do one or the other. Just for comparison, with those 3 things, this would be the way to phrase them in favor of AUD: AUD has the trickiest material, so more time to ponder it and have it “click” could be good. The worst test varies from person to person, and some people have way more trouble with AUD than FAR. And…since you've already taken FAR, you've already seen the rules, so the FAR before AUD rule isn't as set-in-stone.
So, in conclusion, I would still lean towards FAR, but if you have any gut feeling, follow it…because without knowing the inner workings of your brain, the best I can do is give a best guess based on the inner workings of my brain and the reports of others. There's not an absolute “You need to do this one and then that one”, so if you have a preference, you can go with it without a problem. 🙂