In my doula business I hear this all the time, "Wow,thank you for getting back to me so fast!" I am amazed at how long some doulas take to get back to a potential client. I have heard clients complaint over and over again that they wait sometimes three days before they get and email or a phone call back from someone they have called to schedule an interview. If someone is interested in what you have to offer they deserve a phone call or a quick email RIGHT AWAY. Yes even if at that moment I am at a birth, it literally takes me a few seconds to say, I am at a birth right now, but I will get back to you as soon as possible, and....THANK YOU for contacting me. I also make sure I add congratulation on your pregnancy, they are excited and love excitement back.