"I Have a Dream" was largely improvised, but King and his team of writers had toyed with similar themes in other speeches—the early drafts of the big kahuna.

In 1961 and 1962. King gave several speeches called "The American Dream," where he used the phrase "I have a dream." (Source) In 1962, at an African American high school in North Carolina, he gave an hour-long speech with language that closely resembled the seventeen-minute version from 1963. (Source)

Some scholars maintain that the original title of the 1963 speech was a variation on "Normalcy No More "—which is way, way less inspiring.

Others suggest that King toyed with titles related to "the canceled check." The metaphor of a "bad check" elaborated the idea that the promises of the American Revolution excluded African Americans.

Drew Hansen, a King scholar and author of The Dream, wrote that the original title was "Cashing a Canceled Check," and also pointed out that King didn't always compose exact speeches. Instead, he rearranged and edited material from previous speeches to make a new bit. In fact, King and his speechwriters pulled an all-nighter just to cobble the thing together. (Source)

The point of all this is that the speech didn't get the nickname "I Have a Dream" until afterwards. Any "official" title that it might have had disappeared as soon as he started preaching from the pulpit. The fact that we now know it as "I Have a Dream," its name in history and culture, just shows how much of the speech was improvised.

Not bad for a first try.