we went to a wedding with our baby when she was 3 weeks old. it was out of town too and we had a hotel near the venue. i have to say, if it hadn't been a family wedding (and my husband was being the videographer), we would definitely have bailed. Not only will you be tired, you be feeding all the time, changing nappies all the time (I changed our baby in the grave yard of the church before the ceremony, and was breastfeeding her in the church during the vows). Also, depending on your birth, you might not be feeling physically up to it. It is definitely a strain on your body when you would probably feel more comfortable at home. Anyway, like you said, you will know better once your baby is born, I would definitely not promise to go, it will just put pressure on you once the baby has arrived.