Planned, yes. But to what the Vinman said, they had no plans on going ahead with it until the Emperor had time to capitulate. Once he didn't, they went ahead with the second.
Iwo Jima was essentially a dressed rehearsal for a land invasion of Japan to get the Emperor to capitulate. But as vicious as that battle turned out to be, with some 20k killed, it was clear there had to be other solutions than a bloody, prolonged land war on Japanese soil. It was the choice of the lesser of two evils. The debate still goes on which one was lesser, but I would still give the a-bombs the nod on that one.
Even so. Everyone fixates on the atomic bombs -- which today would be classified as puny tactical and not strategic weapons -- and totally miss the magnitude of the
American firebombing campaigns on Japan. These were far more deadly to civilians, and far more questionable in terms of ethics, IMO.
The fact that people are quick to point fingers at the atomic bomb drops and yet make no mention at all of the firebombing campaigns is usually proof that those people have only a few limited slices of knowledge on the topic -- and that they are trying to operate logically well beyond where their own knowledge or understanding of the situation falls off. There's no logical reason why someone would ignore evidence that could support their arguments
even better than the A-bomb drops ... the only explanation is, to be honest, ignorance of the situation.