Milk bottle and UV steriliser

Hi I am a first time mom and would like to check or get an opinion. I'm currently using avent ppsu bottles for my 2MO, 1)how many times a day should we use UV steriliser after every feed? or only once a day and use hot water for every feed afterwards? As I read the instruction it says that UV steriliser may reduce the bottles lifespan 2)how frequent should we change the bottles? #ingintahu #pleasehelp #1stimemom #advicepls