Now that I finally put together the packet and will mail it out, what is my next step, aside for waiting and waiting for the biometrics? what are the next forms I need to fill/mail? when can I start working on citizenship?

Thanks

The next step is receipt of your application and extension of your current green card up to one year. After that will come the biometrics letter with appointment and new case number. You can use this number to get set up on email notification.

After biometrics is done, then you get to wait. Welcome to the waiting party.

Citizenship is optional, and there are a bunch of separate requirements, so I don't know exactly when you'll meet each of them.

But if you're married to and living with a US Citizen, you'll probably be eligible to send in your citizenship paperwork a year after you were eligible to send in your I-751.

On the day you send in your paperwork, you must have been married to and living with a US Citizen for a full three years. You must have held LPR status (whether conditional or not, doesn't matter) for three years less 90 days. There are other requirements regarding number of days outside the US, but if you primarily lived in the US and only occasionally took short vacations outside the US, you'll probably be ok on this.

See The M-476 Guide to Naturalization for more details on the requirements.