Oh, this is such a good question I had to really think about it... I think the order is less clear than that!

I think Victor definitely recognized his romantic (and sexual) feelings for Caleb first, and I think it was when he was around two. He also definitely thought "oh my god I'm a monster" and tried to just put it aside and be a good dad.

I think Caleb for his part didn't really... think about it. He definitely thought his dad was attractive and liked cuddling and hugging and being tickled a little too much by the time he was three, but I don't think he conceptualized it as a crush per se.

Things didn't come to a head until Caleb was four. Victor was falling deeper in love, he was trying to keep distant from Caleb to keep him safe. But Caleb was falling deeper in love too, so he responded by becoming more pushy and needy (and overtly horny.)

Finally Victor was very dramatically like "If I don't tell him, I'm going to go insane" and broke down and confessed his feelings. He expected that to be the end, of everything, but Caleb was like "Oh OK :) Me too!" and kissed him on the spot. Caleb showed him exactly how much he meant it that night and the rest is history.