I would go straight to the pen. Make sure the chicks can't get through the pen fencing. I am guessing the flock feed says 6 weeks or older because it is in pellet form, you could also soak it in a bit of water to soften it up for them (but wet feed will turn sour if left outdoors in hot weather for several hours).
I also give the hen/chicks scrambled egg the morning after the hatch. Course if you do that make sure the other birds can't fly into the pen as the food will tempt them. Broody raised chicks are often quite wild so if you want tamer chicks bring them treats and try to sit with them at dusk each night especially when they are tiny (right before bedtime is usually when they are most open to being handled especially when they are 2+ weeks old). Feed them a dish of egg with your hand nearby, then start putting some in your hand to encourage them to come closer. Plus the hen will be more tolerant of your presence if you come bearing good food.