Huh, I thought it was pretty explicit: the maneuver only comes into play in the next exchange...but
you can automatically
choose to inflict a one-shift hit to the
target, drag the target with you one zone, or
inflict a maneuver (like Tangled Up), and then
you must roll the grapple at –1 (the other action
you take is considered supplementary because it
doesn’t require a roll).
Finally, you can also
By that description, you create a maneuver and THEN you do roll the block. Which means you've already got an aspect ready to go. It doesn't really say in the example. The Thug PINS Harry, then rolls a Fair +2 block. It never mentions tagging the PINNED aspect.
I actually like it. In light of this, I'd allow the tag. Since you have to take a -1, you're not getting a full value for your tag anyways. The reason I'd allow this is because not everyone plays grapples the same.
If it were me GMing, I might not allow it. By my reading of the Grapple rules, any successful overcome does not break the grapple. I, typically, make anyone caught in a grapple have to burn an action trying to get out of it. They HAVE to do an action that would be
something that would reasonably break a grapple. An attack action targeting the grappler, an intimidation maneuver targeted at the grappler, an athletics maneuver to SQUIRM away etc...
If the target cannot beat
the block strength of the grapple, it’s assumed
that the grappler is still holding onto him,
giving the grappler his entire set of supplementary
options next round. If the target beats the
grapple strength, however, the action succeeds.
Additionally, if the action is something that
could reasonably break the grapple—an attack,
a spell, even a threatening look—the grapple is
automatically “released.”
So, to me, successfully shooting another target (other than the grappler), for example, will not break the grapple. Therefore the grappler gets a chance to use his fancy Aspect in the next turn.
Lots of people treat grapple blocks exactly the same as a regular block. IE: if any action overcomes the block, the grapple is broken. Interpreted this way, you almost never get to take advantage of the special actions in a grapple. At least, not in my experience - and I like playing grapplers. If this is how your GM runs it, then I'd allow the grappler to tag the aspect immediately.
Edit: either way, I think I'd allow it. Grapples take lots of time to set up.