If the days are warm and they have shelter and can be locked up tight at night with a heat lamp if needed, they could go out now. I wait til they are mostly feathered, about about 5 or 6 weeks.
I moved mine into the garage till they wre probably around 8 weeks old (not even a year and I barely remember!) but once they found my pond there was no getting them back inside. I live in northern MI so it's colder up here than TN I suspect.