When to harvest?

[SparrowSong]

We have a Wellsummer rooster that is 4 1/2 months right now (not even crowing yet) and a Dominique hen that's a little older. In the spring, we would like to hatch out some eggs for chickens to harvest from these two. We chose them b/c they are the biggest of our flock.

My question is, at what age would you harvest the Wellsummer/Dominique mix birds?

Thanks.