My chicks are 5 weeks old today. Their chicken coop is a building with wood floors covered by industrial rubber matts. They have a heat lamp, a brooder heater and a regular heater run by thermostat. It has been in the high 40's at night. They go in their run for an hour at the time when it is at least 75 degrees. We do this about 3 times each day when possible. They will always live in their house and be closed in at night. The run is very secure and about 12x20. I always stay with them in the run. When can I let them go freely from the house to the run?