Your I-20 package has been sent via U.S.Postal service First class. Your Sevis ID is:********. You may use this number to book an appointment date with the U.S Embassy.
You are better off contacting the AD office directly to check out your admission. Know more about the tuition and fees, as well as any possible scholarship packages they would offer you.
it really depends on what school. Some belong average schools use mass I-20 to get the deposit because they know that they have 30 days grace period to put i-20 in the computer system.