Finasteride shedding

I started using a higher dose of topical finasteride about a month ago and ever since then I have been noticing more hairloss. I do know the so-called “finasteride shed” (initial period where hairloss temporarily increases) but I am surprised that it started literally the day after my first application (I thought it should take some time to start working). I have been monitoring the amount of my hairloss (after washing my hair) for months and nowadays I see about twice as much hair in the bathtub than before. I know that this is probably happening due to finasteride and that it should be a good sign but a part of me still worries that it might be just my hairloss getting more aggressive.

Could you please advise me on how long the increased shedding period should approximately last