The Illithid approaches Lae'zel with a tadpole first, and more hesitating than the next time.
She turns her head away, and he places the tadpole on her cheek, right between her eye and her ear.
[Linked Image]
The (apparently too young) tadpole decided to go for the eye, not the mind flayer.

The second time, with the first-person-person, he is way more confident to do it the same way, since he
a) did not even allow this person to turn the head to the side, he moves it back, and then
b) puts the tadpole right into the eye this time.

He obviously gained confidence between the first and the second time,
maybe by learning that 'he can get these tadpoles into people's heads already',
supporting the thesis that he made this decision spontaneously.

And since he allowed Lae'zel, and only her, to turn her head away, exposing her ear,
he maybe actually expected the tadpole to go there, before learning otherwise.