At 5 weeks, you've only had about ¼ of the dose so far. That result doesn't sound too bad to me, but I'm not familiar with what PSA profile looks like so soon. It takes about 200 days to get all the dose, but it is front-loaded, halving every 60 days.
However, PSA can continue dropping well after that, out to about 3 years max. You may get some PSA bounces in that time too.