Tier 2 (General) Applying from the US

Hi all,
I could really use some help in understanding the process for applying for Tier 2 (general) in the US. Thanks in advance!

I have a really tight timeline to apply and get my visa (7 working days) while I am in San Francisco. I will be paying for priority service (which hopefully means the visa will arrive in 3-5 business days).

What I need to know is the overall process. If I understand correctly it is:
1. Apply and pay online while in the USA.
2. Buy Priority Visa service via VFS
3. Submit documents via mail (next day)
4. Appointment for biometrics.
Please let me know if this is incorrect.

Also, is it easy to get an appointment for biometrics in the US? I really only have one day to get it done!

Thank you!