Health coverage after losing my job: marketplace or Medicaid?

My employer coverage ended at the end of the month and I am trying to work out what to do as a web developer. I have read a lot of threads here and could not find my exact situation. I think my income this year might qualify for a subsidy. How fast did coverage start?

Thanks for writing this out. I went through something close to it 12 months ago, and it settled down once I kept a simple log of every call and form.