lcwra query

hi, me and my partner have been on a joint uc claim since april 2019. Since then we have continued to send in sick notes. I filled in the work capability form but never heard anything back and continued to send in the sick notes. At the beginning of feb we breifly split up. Around a week later when we went back on to the joint claim i was asked on the phone why my partner had never had a work capability assessment. I explained that i had sent off the form and never heard anything back, the advisor on the phone told me they had received it last year but basically nothing was done about it. My partner finally had a telephone based work capability assessment last thursday and we have received a letter today saying he has been placed in lcwra and that if any money is owed we will receive a letter in 7 working days to confirm this. When i called uc earlier they confirmed they sick notes on the system from 3rd may onwards. I understand that there is a 3 month wait from when you start sending in sick notes to get any extra money if you are entitled to it. Does this mean he would receive a back payment from august last year? Any help would be appreciated.