The song starts out with:
One for the money
Two for the show
Three to get ready
And-a here I go
It's very similar to the beginning of "Blue Suede Shoes" (either Perkins' original or Elvis' version):
Well, it's a-one for the moneyAt first, I thought "Watcha' Gonna Do" was copying that part of "Blue Suede Shoes," but I lookt up the dates to find that "Watcha' Gonna Do" is from 1953, and "Blue Suede Shoes" is from 1956. So either "Blue Suede Shoes" took that phrase from "Watcha' Gonna Do" (which seems unlikely to me) or "One for the money..." is an older than either. I remember reading something about how Haley used to take phrases he heard and put them into his songs, so maybe this is an instance of that.
Two for the show
Three to get ready
Now go, cat, go
The other thing I noticed is the mention of peaches and tree-shaking in the second verse:
Once we were happyI found this same metaphor in versions of "Matchbox" by Jerry Lee Lewis and by the Beatles and in the Steve Miller Band's "The Joker." Originally, I thought that "The Joker" took that from "Matchbox," but last fall I also found it in Don McLean's "I'm Sitting on Top of the World," a song originally from the 1930s that predates all of these. So it seems that "Watcha' Gonna Do" is just an-other song that took that peaches and tree-shaking metaphor.
Happy as could be
You didn't like my peaches
So you shook another tree