finasteride generally starts working right away, the hairs you shed are probably the weak ones that are gonna regrow thicker. id say a month and a half in is a quite normal time for your ****ty hairs to start going to start making way for new ones. it might take 2 or 3 fallouts for each follicle to get stronger.
there is no science behind this. if I was OP i'd be very cautious if I suddenly started shedding a lot of hair after taking finasteride
