Change of circumstances within 12 months from original award

Hello. I have a question as seen lots of different articles on internet and I’m confused. I have been awarded pip on December 2022 with only enhanced rate for daily living. For mobility I’ve score not enough points. However my circumstances has change few month after I’ve been awarded and just been worse. I’ve applied and been granted blue badge and on assessment advised to inform DWP about change circumstances which I did. I’ve make them aware beginning of September. Form’s received end of September and send back to them first days of October. My assessment has a place middle of December. I have been contacted DWP to send me a copy of the report which they did and I can see as per assessor I should be awarded moth components on enhancing rate. Of course - now case manager needs to make a decision. But my question is. If they will agree with assessor will they backdate payment from September 2023 when I let them know about changes or from 2022 when my claim was originally made? I’ve seen some information where it’s says if changes occur within 13months from original claim then they will backed from that date (this 2022 in my case). Not sure if this is or not correct. Can anyone had some knowledge regarding this?