I usually find that when I open up with some girls, and I am confident, then when I smile at them they smile back, and in general they are already mirroring me and are in rapport, though this depends girl to girl, but can smiling back in rapport be counted as IOI.

not really, remember female to male attraction should come before rapport/comfort. Figure that out and your 32.7% of the way to PUA mastery.

Is it possible that you can create attraction with your own IOI, and then she responds with her IOI, or it has to be this involuntary IOI initiated from her side.

How did you come to this figure 32.7%, is there a reference, if at all you were serious.

Trying to elicit an IoI by giving an IoI is exactly what most AFC's try to do as soon as they can. Trading status for acceptance. Guess what, that works with guys, but it doesn't work with girls. If you operate under this mindset you can get laid on occasion but that isn't good game.

The secret is to be attractive to woman but creating emotion, interest, mystery, intrigue, credibility etc. Have them Show IoI's and then through qualification and other methods you show IoI's. Now that's good game!

32.7 is an arbitrary figure I used in humor, my point is that its a huge part of the game. I'm sill trying to get better at this myself.