Prostate cancer

Age 62 gleason score 7 Metastatic prostate cancer, post TURP and bilateral orchidectomy, 1 yr back initially the PSA was 29 before surgery after it the baseline PSA was 0.25 now PSA monitoring was done monthly throughout the whole year and it Ranges from 0.01-0.05 and now it has becomes 0.09 I want to ask where the when it should be something to worry about alarming and when is chemotherapy started.