(A quick aside: The naming of the clients, servers and services known by codename Office 15 is fairly confusing. Products with "2013" in the name -- like Office 2013 or Exchange Server 2013 -- seem to be the on-premises/locally installed versions. "Office Next" seems to be the way Microsoft is referring to versions of Office sold on a subscription basis, as well as cloud versions of its Office wares, such as the next version of Exchange Online.)
In an Office News blog post on October 11, Microsoft execs noted what they've been trickling out recently: the set of client apps, servers and services in the "Office 15" wave will be released in several stages.
Volume licensees will be able to get their hands on the RTM bits as of mid-November 2012. (TechNet and MSDN subscribers will get the same access). Office 365 subscribers also will get all the new hosted-server bits starting in mid-November.
In Q1 2013, the new Office releases will be generally/commercially available to consumers. In other words, that's when the new home and small-business subscription-based versions of Office -- branded as Office 365 -- will be available for purchase. I've been hearing February 2013 is the date when this will happen. But given the Office team has RTM'd earlier than expected, maybe the Office 365 Home Premium, Small Business Premium and Office 2013 releases will be early too....
Microsoft officials said earlier this fall that the Windows RT version of Office Home & Student -- which will be included with Windows RT-based machines, including the Microsoft Surface RT -- will start rolling out to users as of early November.