Losing employer insurance, where should I look? (update)

My employer coverage ended at the end of the month and I am trying to work out what to do as an electrician's helper. It has been weighing on me all week. The COBRA notice arrived with a very high price. How fast did coverage start?

Losing job-based coverage usually opens a special enrolment window, so check the deadline on the official marketplace site. I missed it by a day once and regretted it.

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