Before I say this, keep in mind that not all cases are the same, and processing time is different from case to case:
They gave my wife the same form in May 17, 2022 for additional documentation, we gave them the requested documentation in 26-May-2022, and the case is still pending since then.
They updated the case several times (date changes), but the status never changed from Ready.
They called my wife for a second interview in February 2023. After the interview, they told her all was good, but we haven't heard a thing yet from them. The last time the case was updated was 10-April-2023, and the case still shows Ready.
Again, not all cases are the same. I think a joint sponsor case should be a lot less complex than a lot of cases, and you should hear from them soon
Good luck