When I was researching minoxidil I found the general consensus was that you can use it for 4 months and if you don't get any re-growth you can stop it no harm done. But if you do get any re-growth and use for more than 4 months,and stop using it, you could end up going through a shed where you loose the Minoxidil dependant hairs and a few more. I 'am no expert but I did do quite a lot of research.
I have been using Minoxidil for two months and can see a lot of miniaturized hairs on my front getting thicker I'm hoping these turn into full mature hairs.