When a person submits their information in a web form, th eir interest in your product or service is at its peak. That is what they are thinking about a t that moment, so if you call them back instantly, they are the most open and interested i n what you have to offer. If you wait, they may forget why they submitted their info in your web form -- and they may even forget doing it at all.
If you call someone back within seconds of the time they submitt ed the web form, they are usually very impressed. This speed of response makes you and your company appear to be very professional, very trustworthy, very responsive. T his can give the person a high level of confidence in your ability to deliver, and make them much more likely to become your client.