That is about my guess as well.
I do not expect that Tesla will release any more Model 3 info in 2016.
This pre-order, though, is earlier than any other Tesla pre-order and with far larger numbers. I think they will have to "update" reservation holders every once in a while, maybe every 3 months.
People will get antsy over 18 months; we have nearly 400,000 who've put down $1000. And I'm talking about normal people getting antsy, not just this TMC crowd, haha.
Remember: Chevy will release 3 iterations of the Bolt by the time Tesla reaches max production rate for the Model 3: the 2016 Bolt, the 2017 Bolt, and the 2018 Bolt.