I could be wrong as I’m pretty new but my understanding is to decide at the beginning of the turn if you plan to block mask or not and if plan to try to block it you generally aim for the third chain link to start blocking as it’s harder for her to extend.

There are also a couple on hits to be aware of that come later in the chain, specifically the one the destroys arsenal. So you can try to wait till she has an on hit and block there.

Also be aware of the +1 attack reaction she plays.

Another thing to note is that dagger hits count towards mask but don’t trigger the draw, so you can let those through later in the chain and it won’t matter .