I have PCOS, so my dosage of PM will be different than the average woman.
I produce very little estrogen naturally, so my current dose of 1,000mg isn't doing anything for me. Next cycle I'm going to start at 2,500mg or so for the first few days, to sort of "kick start" some growth, then drop down to 1,500 or 2,000mg and see how that works.
I've found that for me, personally, taking it all month delayed my monthly happening by two weeks, maybe a little over. This month I took my "regular" dose of 1,000mg for two weeks, then dropped down to 500mg for the second half of my cycle. I stop it completely for 5 days each month to allow my body to finish its cycle. Some people take it all month no problem, but this month, this is what's working for me as far as keeping everything on time and preventing extra cramp pain.
This is only my second month on PM, and my dose obviously isn't high enough, so no growth yet. But when I first took it I did notice my nipples became sensitive for the first time in my life! So I have faith that it will work very well once I find a high enough dose for my body.
Most women don't take more than 1,000mg a day, but biological males take as much as 3,000mg and up, so it really depends on your natural levels and what your body responds to. Start out slow, then increase the dose very slowly if your body doesn't respond.
Also, PM is VERY strong (which is why most women don't need over 1,000mg), so they usually end up needing Progesterone Cream to balance out their hormones and prevent estrogen dominance. I use mine the last two weeks of my cycle, once I've dropped down my dose for the month. I also use a little more than I'm supposed to, because my body produces very little of that as well. But many women can get away only using it once every three months or so, because it stays in your body for quite a while.
PM's a pretty tricky herb, so it'll be trial and error to find out what exactly works for you. Heck, I'm two months in and I'm still in the trial and error phase!