
Quoting
flyingron
The SSA does NOT have anything to do with what a legal name change is. It's a common misconception, but it's completely untrue. The SSA has rules for what they will accept for a legal name, but they neither effect nor arbitrate what your legal name is.
If you want to change your name, you need to make sure it is in your divorce decree. When your decree is issued, then you have a LEGAL name change. I'd get a few extra true copies of the order so you can send them/show them to the various people you will have to convince your name has changed: Social Security, the DMV, etc...
You're free to call yourself what you want, prior to the divorce, but anything that requires a legal name will have to wait until the divorce order.
Your other option if you want to jump the gun, is to get a court order of a name change NOW. In most cases it's straight forward and inexpensive ($65).