The best time for you to travel with your baby depends on his condition, your condition and the weather. If your child is not feeling well, then it is best to cancel the trip and reschedule it until your baby has fully recovered. If you are not feeling well, the same option should apply as you will only have a hard time coping with activities. If the weather is bad, it would be a lot better to cancel the trip just the same, as it will not be a comfortable trip not for everyone.
But if the things mentioned above are in good condition and as long as you have really good car seats, then you are set for a car trip. But of course, air travel is a different story. Your newborn baby can already travel by plane in four to six weeks, but this is not advisable. This is due to the fact that, at this stage, your baby is susceptible to various types of communicable diseases, and letting her into a plane with lots of people and where the air is circulating just within it is not a good idea. Your baby might catch a cold or may even suffer from fever.