Granted I'm not an expert on this, and the picture isn't that clear, but I don't see the signature bite marks you'd see with AEFW, not to mention I don't think they typically go up one branch, you'd see them stay down low around the base.
What you have there looks more like a tissue necrosis.
But again I've never had personal experience with them *knocks on wood*
You also may want to check your phosphate level as the skeleton normally doesn't turn green that quick unless you've got a phosphate problem.
I battled aefw and that damage does not look similar. When it comes to how long it takes them to wipe out a small colony... it depends how many there are. Mine came in on an efflo frag and were in the tank 3 months before I found out they were there. I kept assuming the damage in the efflo crevaces was a water flow problem and then finally dipped it in TMPCC (tropic marin pro coral cure) and had over 40 of them come off... I lost a lot of acros from those rotten pests. QT all the way baby! Can't dip and toss em in the tank because the dip won't kill the eggs.
My issue is I thought I had AEFWs on one piece. I treatred it and only a few of the regular flatworms came off. It has recoverd and almost back to preissue condition. It has even started a few new branches. On another piece I noticed questionable damage a few months back and left it alone. What makes me think it is not AEFW is the damage is not on the underside parts, but more mid branch. The base has no damage at all. The piece is well on it's way to recovery. It's starting to get it's color back and grow. None of the other pieces in my tank show any thing at all. I think I may have had a nipping fish or other critter. If it was my CBB I will find out soon since it died two days ago. Could it have been some snail, starfish or other thing that has since been eaten by a fish or just flat out died?