That happened to me as well, while doing a fresh install (i.e. - I had wiped my drive prior to installing EC); I bailed on the install and did some research. One suggestion was to turn off the wifi while installing; I did so and the second install was smooth sailing. It still hung on the 'less than a minute' message but only for about 5 minutes. YMMV.
This has been going on with various editions of OS X for quite a while; if you Google OS X less than a second (or minute), you will get numerous hits, including from these forums.