When To Let Kitten Roam House?

I have had my kitten for about three weeks now and I want to let him/her out, but it’s so cold outside that I just can’t. He or she is still getting use to me being at home 24/7 since I work the second shift. It doesn’t seem like he or she wants to go out yet, but when he does he always comes right back in. Now this doesn’t happen everyday, maybe once a week if that…So what do you think? Should i let them run around or are they going to be okay?