gums;
https://www.youtube.com/watch?v=0mCFxAsmnk0
This video below looks rearward at the moment of launch, through engine-start and the pitch-up/climb then the apogee and pitch-over. You can see the feathers working.
More interestingly however, the CVR is heard. I'm sure you'll be familiar with some of the sounds as the gee builds during the pitch-up.
Regarding the "unlock" question, from the video/CVR:
Release occurs @ 00:18 into the video. Engine light-off occurs at 00:22"
From crew comments heard on the CVR, unlocking the "feathers" is done @ 00:39, 17" shortly after initial engine light-off.
Actual release of the feathers, ("feather up" comment), near/at apogee for the descent occurs @ 01:18, or 49" after initial unlocking.
We don't have Mach information so don't know at what Mach the unlocking occurred.
The point is, unlocking shortly after engine light-off does not seem unusual according to this video.
In other words, the feathers aren't unlocked just before they're commanded to change position.
Perhaps something in the interlocks, (unlocked, not released) permitted the "feathers" to move; their relatively small structure seems (intuitively...not an engineer!), that they would not tolerate lateral loads well.
As we would know well, once such a failure mode started it would swiftly progress in the same manner as any airplane that had lost its rudder.