I stay on almost permanently. Never off for more than a couple weeks to one month. I use 25mg per day. Half life is around 2 days. I know guys that take 50mg every day and haven't come off for years. I know guys on half that and have also stayed on for years. They use it as their trt instead of test injections.
My doc has patients that take 50mg per day and no test. They maintain their levels that way.
If you have never included it in your trt, along with injections, before then I would use it for 6 weeks and get tested. Then you can see if it raises your test level more than injection alone, good indication it's working
Also, keep an eye on testicular volume and ejaculate volume to tell if it helps. I see a pronounced difference in all three categories.
Sorry.....I know I'm kinda repeating myself. Good luck bro.