yeah my minoxidil shed started at 2 or 3 weeks in as well, and it was pretty bad, i lost about half of the density at the front (balding area) which is alot more than most people seem to be shedding. hope yours isn't as bad, there was a time when it felt hopeless and my hair looked terrible but the thing to remember that the shed is a good thing.
things are still going very well for my sad hairline. i'm estimating NW1.5 by july. the best part is having the texture of your hair come back, because those sparse vellus hairs feel like total death.