When does my employer coverage actually end? - 3 months and counting

I was told my coverage ends on my last day, but the letter says the end of the month. I have read a lot of threads here and could not find my exact situation. The letter is unclear about dental and vision. What should I do about appointments?

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

Dental and vision sometimes end on a different date from medical. Mine did.