Tsst* I wouldn't doubt a lion share of the Romulan population fleeing Romulus before the nova hit. If it was slow enough to explode and Spock being able to travel to Romulus from Vulcan in almost the nick of time to absorb it into the black hole, then I could see the Rommies leaving en masse. The military definitely, civilians yes, the Praetor and senate for sure. The Remans, unlikely they made it. Nero and his crew probably those people who in the face of a natural disaster (Hurricane Sandy/Katrina) know the warning but don't think to move their families away from home.
Hell even the Klingons abandoned their planet when Praxis exploded. Klingons are said to be stubborn and pig headed.