Health coverage after losing my job: marketplace or Medicaid? - any advice?

I have 18 weeks left on my current insurance and I am comparing options. Thank you in advance. I do not want a gap in coverage. How fast did coverage start?

Keep everything in writing and save the confirmation numbers. It saved me later.

Thanks for writing this out. I went through something close to it 7 months ago, and it settled down once I kept a simple log of every call and form.