Confused about when ACA compliant insurance starts covering me

I am planning on getting sterilization surgery soon. I don’t have insurance at the moment, but found out that for the exact surgery I want, ACA compliant insurance is required to cover 100% of the costs as long as it billed correctly with the right codes. However, depending on how elections go, it’s possible sterilization procedures will no longer be covered after inaugeration.

So I started looking into an ACA compliant insurance to apply for asap so I can get this surgery done before inaugeration and still have it paid for, but I was told that I can only apply for this type of insurance starting November 1st, no earlier. So I made a post on reddit explaining my situation and asking how soon after starting the insurance can it cover my surgery, and from the anwers I got, I was told that if I apply on Nov 1st, it sort of just depends on the individual insurance company, some might require up to a 30 day waiting period, while others will start covering you immediately with no wait time. So what I was told was that by December, I should be good to go to have the surgery and have it covered by insurance.

So I booked my consultation for the surgery and had the appointment today. I paid out of pocket for this but let my doctor know I will be getting insurance Nov 1st and can schedule the surgery afterwards. So the surgery is now scheduled for Dec 6th. When I got home and told my mom the news, she immediately asked why the heck I scheduled it for December when the insurance wont start covering me until January. I got super confused because I was told I could get coverage starting in November/December, not that I would have to wait until the new year to start getting covered. I haven’t actually called the insurance companies to ask, because I still need to apply and I’m waiting for November for that. When I search up certain ACA complaint insurances, I see websites come up that claim you can apply now and start getting coverage the same day.

Pretty much I’m confused. In short word, I need to get an ACA complaint insurance. My surgery is scheduled for Dec 6th, but is that too early? Should I reschedule my surgery for January? If so hopefully the doctor has availabilites between the 1-20th… If there is a way for insurance to cover me sooner than January, where do I apply for that? And when do I apply?

This is one of those situations where I just really need to get this surgery done before January 20th. I’m on a tight deadline here and I’m worried about dragging it out too long, which is why ideally I’d love to do the surgery in December rather than waiting until January. I’m just so confused now about applying and coverage etc. When do I start getting covered?

Sorry if this is an obvious question. I have never had insurance before for anything, except when I was still under my parents for other stuff. But I’ve never had health insurance so I have no idea how this stuff works.