As an East Coast non-owner who reserved in Sept. of '16, I'm getting pretty concerned about bridging the gap until the 3. The site currently says mid-2018 for a base model, and that would be entirely do-able by me. But I have a 14-year-old Prius that will be at 200K miles by mid-2018...
@hcsharp is correct, 200K miles is not that many on a Prius, or likely most Toyotas. My last two vehicles were Toyotas with well over 200K miles, my current Corolla has over 170K right now and should be at almost 190K when I get my 3. I plan to give it (the Corolla) to my son who, I hope, will get a few more years out of it.200k is not that many miles for a Prius.
To answer your question though, my delivery estimate for SR is early 2018, for a few reasons I won't take delivery until August though so I think I'll be ok, even if there is a little delay in the estimates.