Can You Bee Paid by Milestones for Contracts Started on the Project Catalogue?

[m-myra]

Hello guys, 

I have checked, but I need to confirm in case I missed something. I have a client who bought a project from my catalogue. She established the milestones, we signed the NDA and started work. Now she just requested that I activate partial payments for the job so that she can pay for the first milestone. I didn't even know that that was an option and I can't seem to find it anywhere. Is there a workaround or do we just set up a different contract with payments made per milestone?