I tried them. You take them for 5 days, what cycle days you choose is up to you. Common choices are 2-6, 3-7, 5-9. I did 3-7. Taking it earlier makes more follicles grow, taking it later makes the lead follicle mature.
They are half as strong as clomid. Most ladies start on a dose of 50 clomid, so you may want to start on 100 of soy. You should take the same dose on every cycle day, not increase it as the days go on as it says on some internet pages.
It is advised you should only take it for 6 consecutive cycles, then take a break before continuing if you wish to do so.
I did ov on my first cycle taking soy but I don't know if it was coincidence or not as I didn't ov on the other cycles I took it for.