You will not automatically get a greencard on the day she naturalizes. Check out the Visa Bulletin for January, there was a retrogression. The approval date is irrelevant, the priority date is the FILING DATE. If that date is current, you still could not file as an F2A spouse because you are out of status.
The Immediate Relative of a USC does not have a Priority Date like those in numerically limited categories. The approved I-130 is all that is needed for an IR to file an I-485, I-131, and I-765 as long as they made a lawful entry and are otherwise admissible as an immigrant. The overstay is forgiven for an IR of a USC. However, depending on the amount of unlawful presence that has built up, an I-131 would be useless and unwise to file. Unlawful presence of 180 days triggers the re-entry bar even for an IR of a USC if they depart the U.S. before obtaining a greencard. Immigration law is somewhat forgiving to an IR of a USC, but not that forgiving.
The fact of naturalization of an LPR petitioner is the basis for requesting an upgrade to the processing. In the situation you describe, once the spouse naturalizes, make a copy of the signed naturalization certificate and submit it with the I-130 approval notice along with the adjustment applications and supporting documentation. If YOU, the adjustment applicant, already have an A#, be sure to use it on the I-485, if not, one will be assigned upon filing. It is not good to have more than one A-file as that will just cause problems later on.