I personally think folks want things as fast as possible. It takes a lot of time to schedule and actually drive to the estimate.
We simply have the customer take 1 photo of each side of the home, text it to us. Then we count the windows and send a reply using a pre saved message that we just add the total number to. It also asks for the customers details . So if they reply all the info including photos are there to book the job when we get back to the office. Very fast and easy. I was very reluctant to start this type of estimates. I was shocked how people loved how fast and easy it was and it saved us TONS AND TONS of time driving all over the city.