i think it works after a month or two. keep at it if you're planning to keep at it anyway, no harm involved i think. if things get bad because of it, you can always stop it.
I saw vellus hairs at around 6 weeks. Got short terminal hairs at the 2 month mark. I'm now closing in on the 3 month mark and have sort of stayed the same as I was 4 weeks ago only that there are a little more vellus hairs on the temples (nothing extraordinary though).
Can't complain about the crown. It has really improved.