Nearly all of the packets we sell will have at least 200 seeds in them, regardless of species. Butterfly weed will have at least 200. (We'll work on adding that info on the product pages.) A lot of milkweeds will germinate without a cold moist period that they normally get over winter, but will germinate more vigorously if they have 3 to 6 weeks or more of exposure to winter conditions. So yes, you should sow them sometime between November and January.