At what age are lambs slaughtered for food?

I have 2 tiny lambs down the street form me and was admiring them. When I told my my mom about these 1 week old babies, she mentioned that they are most likely for easter lamb dinner and I always thought that the lamb on your plate is 6 months to a year old before being killed for food. Could these week old youngsters really be dinner a week from now, or are they most likely "spring" lambs that will be slaughtered for x-mas dinner...poor babies.