Sleeping Bag Rating Question for March Start

Hey all, I am starting NOBO around March 14th. I currently have a 20 degree Enlightened Equipment Quilt.

1. In your experience, will the 20 degree cut it?
2. If I need more, do you recommend a 0 degree bag, a 10 degree bag, or adding a liner to my 20 degree quilt that I already own?

I use an inflatable sleeping pad with a proper R value over 5. Money is not an issue but if I don't need to buy a new quilt, I prefer not to.

Thanks in advance!