First mover has always been a bit of a myth.  For example see (along with other sections of the same page): http://en.wikipedia.org/wiki/First-mover_advantage#Second-mover_advantage

First mover advantage is often cited by some Bitcoin proponents who try to declare the competition over and themselves the winner. It is either wishful thinking, mistaken thinking, willful attempt to deceive for personal gain, or some combination of these.