Earliest application date following visa extension delays

[Chris2804]

Hello,
My wife entered the UK on the 5-year partner route on 3rd October 2017. Her first visa expired on 5th June 2020 but her extension application decision was delayed firstly due to the covid pandemic and then due to a Home Office error. She was finally granted her visa extension on 8th March 2021, with an expiry of 22nd September 2023.
Will these delays impact on when she can apply for Indefinite Leave to Remain?
Can she apply as of 3rd October 2022 (i.e five years after she first entered the UK) or does she have to wait until her visa has expired (i.e 22nd September 2023)? If the latter, this would be almost six years after she entered the UK?
Any advice would be greatly appreciated. Thank you.

[CR001]

No sooner than within 28 days before the 5th anniversary of the date she entered the UK on a spouse visa (not a 6 months fiance visa). The latest she can apply is before the visa expiry date.

[Chris2804]

Thought so, but thank you very much for confirming so quickly