Sorry for the late reply
The thing is, 11 frames is way too fast to react to on pure visual reaction. In fact, the average for fighting game players tends to be somewhere around 20 frames, and for most regular people, it's definitely higher.
There's been enough research on thing topic in gaming in general. However, you might want to try Teyah's "Millia Mixup Blocker", which is basically a reaction speed benchmarking tool.
http://www.teyah.net/MilliaBlocker_v0.3.swf
The interesting thing here is the fact that the examples used to test reaction speeds here (Milia's many overheads, the slowest which is 20 frames) are manageable in actual play. But when done at random however, they actually prove quite difficult to react to, since it's hard to really "predict" a random number generator.
If you really need a visual cue, then you're going to have to learn these on a per player basis, looking for certain player specific cues to know when they're going for a throw.