It’s best to buy a Travel Medical insurance policy after your family plans their travel dates and receive their visas, but before departing to the U.S. Keep in mind, the effective dates of coverage should correspond to your family’s visa. You want to make sure coverage begins from the beginning of your trip. If the plans change, you can cancel the policy for a refund. You don’t want to wait for the last moment and forget buying it, which usually happens as travelers get busy in packing, shopping and researching the places to visit.