I'm just really waiting for global warming to kick in so I can transplant the starter plants into the garden. Maybe May 1st?
Mother's Day is the rule of thumb.
Both are close enough to each other, though you'll always want to check out the 10d forecast before making a commitment.
And for more information that you'd ever like: https://ag.purdue.edu/indiana-state-climate/freeze-frost-probability-growing-season-length/