Lawrence, 25, said that she has finished co-writing the script with Schumer, 34, and that the pair will begin next steps on the project "soon."
"We have finished writing it," The Hunger Games star told BBC 6 Music. "We have an official first draft. I am going to try and fit it somewhere into my ghoulish schedule."
As expected, Lawrence couldn't help but gush about how much fun she had while working with Schumer.
"It was hilarious, because when you're writing a comedy it's not good enough unless you're laughing out loud," she explained. "So I'm laughing at my pages and I'm laughing at her pages and thinking that the whole process is hilarious."
"I'm thinking we've got a pretty funny, good movie," she added.
The two first announced this summer that they were working on a screenplay together – and the real-life friends would play sisters.
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Lawrence also previously dished on the plot details of the movie, calling it "funny," "dirty" and "real."
"Amy, in this movie, she has it very together. It's her lifelong dream to be a flight attendant," she said. "She works at the airport."
As for Lawrence, her character seems to have more in common with Schumer's Trainwreck alter ego. "I'm a MESS," Lawrence joked of her role.