DRP 2.0 Deadline to Sign the Separation Agreement?

I'm a USDA-APHIS employee, seriously considering the DRP 2.0. I just received the contract to sign but there's no information on when I need to sign/submit. I'm under 40, so don't get the 45 days or 7 days to rescind. Does anyone know when I need to sign if I decide to opt-in? I want time to look it over with a lawyer.