May 22nd — NA1 upgraded
The first release weekend is when we at salesforce.com and any customers on NA1 get upgraded.
June 5th — The second release weekend
This is when another set of instances — NA6, NA7, NA8, NA9, NA17, NA18, NA22 and EU5 — gets upgraded. Check out our Trust page to see when you’ll be upgraded.
June 12th and 13th — The final release weekend
All remaining Salesforce systems will be upgraded over this weekend. This is also the upgrade weekend for any Sandboxes you’ve opted not to include in the Sandbox preview.
Is NA1 specifically reserved for Salesforce's internal use and for select customers or can anyone get an instance on NA1?
My assumption is that Salesforce are dogfooding it against their own orgs before releasing it to the other pods.
I'd really like to get a developer edition instance on there to test out Summer `15 release features before they reach my packaging orgs.
I guess I could keep creating new developer edition orgs in the hope of getting one on NA1, but I'm not sure if accounts are randomly allocated to the available pods.