etymology - What is the history and geographic area of the word "finna?"

In St. Louis, I learned of the word, "finna." I know it is slang/contraction for "fixing to." By asking dozens of people, I've learned that it is used by people of many different races and cultural backgrounds. I've also learned that many who use this word have been using it all their lives (for some, that means at least 50 years).

What I want to know is:

1. When did "finna" first start being used?




2. Where did it originally came from?




3. How far geographically has the usage of this word spread from its original location?