You keep an eye on the Visa Bulletin (released monthly). Table A is what you need to look at to see when a visa will become available to her, when her PD is before that date - not sure which country she's in, but for most countries the date is 8th June 2007, so anybody that applied before that date is now able to get a visa https://travel.state.gov/content/travel/en/legal/visa-law0/visa-bulletin/2024/visa-bulletin-for-march-2024.html
And as @Chancy said, Table B tells you when you can complete the NVC side of things, that's currently at 1st March 2008.
Good luck.