Adding in my experience here:
Location: Connecticut (Online order)
Approx. Time Reserved: 10:30PM ET, March 31, 2016
Reservation #:RN10853XXXX (from MyTesla page)
Email Received: No
My reservation was completed just as the official tweet went out that online orders were being accepted, so I must have hit refresh on the web page at just the right moment to get that time slot. By the time I switched browser tabs and logged into my credit card account, the transaction was already posted in the pending section. Had no luck getting on My Tesla all day until I got a few second glimpse around 1PM ET today. Grabbed a screen shot with the reservation number, updated my contact info (added an alternate contact) and hit save, then their site crashed. Around 5PM I was finally able to get back in. My contact change went through and now I'm able to get to the site without too many issues. No email yet, but per Tesla's twitter account, they should be going out within 24 hours or so.