Quick question re:cold stratification

I’m currently setting up my seeds for winter sowing and I have a question re: time periods for cold stratification. For example, 60 days, 30 days, etc.

Do I need to wait until next month to set out my 30 day seeds or can I put them out with the rest even though they’ll spend at least double that in the cold? I mean, I have to imagine that milkweed or whatever aren’t keeping their seeds warm and away from the ground until winter is almost over.

Thanks!