Anytime. You may travel with your baby anytime. Minimizing travel in the first 8 weeks is advised since your baby's immune system is still very immature. A well thought out plan can make travel an enjoyable experience. Consult your doctor if you are planning international travel.
After 2 month shots. Travelling exposes your newborn to strangers and unknown environments. This potentially increases the risk of your baby becoming ill.So, a general rule of thumb is to wait until she has received her 2-month vaccines. Then she is develpmentally more mature, better able to withstand the physical rigors of travel. You will understand her "language" by then, allowing you to better appease her.