We didn't take DS out at night for the first month, not because we were worried about the cold, but because he was more grizzly in the evenings and we were settling into our routine for bed etc. Now we take him out ( he's now nearly 7 weeks old) but mostly to families houses. We thought it would be harder in the evening cause of his grizzles but it's actually easier with so many hands ready to give him a cuddle if he cries so we can finish dinner etc. I wasn't concerned about cold cause he was rugged up for the short walk to and from the car. And it didn't seem to disrupt his evening routine. I wanted him to get used to going out cause we regularly would go and have dinners with my parents, in laws, brothers etc. And it's fun being around the family with him and the other kids. Good family atmosphere.