Hm, that's not what I thought...
When your target frame is 15 for example, and you have the following pattern :
12 - E
13 - E
14 - K
15 - P
For a monster frame of 1 (we'll take the suicune milanda was trying to catch), you call until you see EEK, doing so, since you have seen the "K", you are now on frame 15, and the suicune will have the spread from frame 15 when you battle it
The way I see it : monster frame of 1 you stop on target frame, monster frame of 2 you stop one frame before target (here it would be after you see EE, and you would be on frame 14), monster frame of 3 you stop 2 frames before target, etc
Am I correct ?