When is a good age for a dad and new baby to take a trip alone together? I would like to use this as an exercise for them to bond. And for hubby to get into the groove of being proactive and independent. He needs to know how to look after baby when I am not around.

If you're talking about a vacation, start with a nearby place or a staycation in case of emergencies. If he hasn't taken care of the baby for an entire day by himself yet, then I'd think it's a bit too ambitious to let them take a trip together. A good age would be when the child is able to walk and talk, so it'll be more fun for both of them.