You have to at least have an itinerary you do not have to have the hotel and the airline booked until they approve your Visa you do have to have them to get your c o e because they will request that and the receipt of payment for both before issuing.
Most of, if not all Embassy locations are doing applications for visa's online, if you are approved then they request you mail documents with a insurance policy of $100,000.00 in covid coverage...