Never understood why MSFT announced Surface so early

I then listened to Panos Panay, GM of Microsoft’s Surface division, talk about wanting to control the messaging around Surface. He talked about how Microsoft’s June 18th event was scheduled because Surface was about to hit a point in its production where he could no longer guarantee there wouldn’t be substantial leaks about what the product actually was.
http://www.anandtech.com/show/6385/microsoft-surface-review


I guess it makes sense now, especially considering that we had to wait so long before we got a price, and the event seemed like it was very out of the blue. But I'm not so sure they made the right decision. Would it have been better to have a rumor mill about their future tablet for months then unveil the week before launch? I guess they took the idea of being on their terms and controlling the message to the extreme.