The new Yes as we know it was announced in September 2008 (although the idea of Yes moving on without Anderson was mooted as early as June 2008 in the initial panicked reaction to Anderson's ill health). That same month, the idea of doing an album at some point is mentioned in interviews. We'll take September 2008 as the starting date.
The idea of Anderson Wakeman Rabin, or Anderson Bruford Wakeman Rabin as the initial plan was, dates back to February 2010. Wakeman, without naming names, first described the project and plans for an album that month.
But it's one thing to moot doing an album at some point. That's not the same as really starting work. Of course, musicians are of always writing and often use older ideas, so this is difficult to assess. Still, let's try to identify when we first see serious and collaborative work towards an album. For Yes, that would seem to be September 2009 when Squire, Howe and O. Wakeman gathered to exchange ideas specifically for a new album. With AWR, it would appear to be January 2011, when Anderson first says that he and Wakeman have written material for the project (whereas his 2010 interviews talk of writing in the future). So, this first step took 12 months for Yes and 11 months for AWR.
For Yes, recording sessions began in October 2010, another 13 months on. Recording finished in February 2011 (3 months more) and the album was mastered in May 2011 for a June 2011 release. Presuming that happens to plan, that's 3 months from recording finished, 6 months from recording beginning, 19 months from joint writing beginning, 31 months from the project beginning.
AWR started later. To stay one month ahead of Yes, they need to start recording by February 2012 and aim for a September 2012 release. OK then, clock ticking...