I don't worm this young, on the grounds that they haven't really had chance to pick up many worms yet.
Once they're onto layers pellets, I worm them with the rest of the flock, which i do every 6 months. So they get done when the rest are due.
I use flubenvet, which is mixed into the food for a week. I have started to buy Marriage's ready-mixed food and just feed that for a week as it makes life much easier.