Xbox Next - the right time to announce?

With the PS4 announcement upon us I was thinking how incredibly early it is for a next-gen product announcement.

Assuming availability in November we still have 8 or 9 months to wait.

I'm almost certain that whatever "mainstream media" buzz Sony get from this announcement will well and truly fizzle out before launch.

With that in mind... when do you think is the right time for Microsoft to announce the next-gen Xbox?

Announcing before E3 (June) still leaves a 5 month gap between announcement and launch.

Announcing at E3 might get crowded out by all the other news.

Announcing after E3 means Microsoft would miss out on any publicity directed toward next-gen games during E3.

I was also thinking of two recent product announcements by Microsoft.

The Windows Phone 8 launch was effectively spread out over multiple events. I think by releasing information piece by piece they missed out on launch buzz (the leaks didn't help either!)

In contrast the Surface announcement had a huge amount of buzz and was probably the strongest launch event of the year... However I think the long lag time between the announcement and availability prevented Microsoft from capitalizing in that enthusiasm.