When do you buy tickets to the Colesseum underground and attic

In a post here https://www.reddit.com/r/ItalyTravel/comments/1fkp2uq/colosseum_tickets_at_1_am/, a member said tickets go on sale at 9 am for 9 am access and 10 am for 10 am access, etc. Does this apply to underground and attick? That wasn't made clear.

Also, do these tickets go on sale 30 days prior? We are going to be there Dec 3-10, and we would love to be able to see those areas. It is winter, but it is also a holy week with the 8th being a holiday, so we aren't sure what to expect.