Seriously, Megha:
This is a massive project and what you are to prepare is the very foundation of the initiative.
On that scale, a lot of very specific constraints and requirements need to be considered. Doing this without any relevant experience based on a generic template from a completely different project over a weekend probably without access to the customer for clarifying questions is a certain recipe for disaster on multiple levels.
If you work for a consultancy and you can't leave the them for the fraudsters they are, if they sold you into this role, then you need to tell them you need senior coaching. If they don't believe it, you can refer your boss to me for a chat, if he/she wants to and can deal with not only hearing niceties.
Best of luck
Sven