Or just attempt to load a dual-stack site. A few examples off the top of my head: http://www.freebsd.org/ http://www.freebsd.org/ http://www.debian.org/ ht

Or just attempt to load a dual-stack site. A few examples off the top of my head: http://www.freebsd.org/ http://www.freebsd.org/ http://www.debian.org/ http://www.debian.org/ http://www.ucla.edu/ http://www.ucla.edu/ Each of those has been dual-stack for years now. If you can load them without an egregious delay then you'll have no problem on June 8th.