Called Iberia today and mentioned that I had created an Iberia Plus account a few hours before booking some flights. Mentioned how the IB # shows up on email confirmations, but for some reason was not on the online flight reservations on my account. Told him how I manually input each one. I asked if people who had just signed up for Iberia numbers right before booking would still be eligible for the Avios promo. He said definitely and that no term excluded those who had just signed up for Iberia number. Asked if any issue since I had to manually add my IB# after the fact and he said no issue since its properly attached to the res now.
He sounded like he was reading a script or had been fed answers to these questions (which isn't necessarily a bad thing if the info he is being fed is correct).