How long is minoxidil shedding supposed to last?

[JP52112]

Hi everyone, been doing minoxidil and propecia combined with daily dermarolling in my right temple since january.
Been shedding for two months almost, only a few hairs a day, but it's constant.
Should I be getting worried? I know effects are seen after four months but shouldn't the shedding have stopped by now?
Thanks for your help