I know others have had no problems with their deliveries from Amazon, but my scheduled delivery was quite a headache. I scheduled to have my set delivered last Thursday between 4-7pm. CEVA called me on Wednesday to "confirm" that my set would be delivered between 2:30 and 5:30, to which i informed them that I wouldn't be home before 4. After numerous calls to both Amazon and CEVA, I received a personal guarantee that my set would be delivered b/w 4 and 7, and that CEVA's local contractor wouldn't be the ones delivering the set (for the sake of brevity, I'm leaving out many of the details).
Long story short, I received a call on Thursday at 2pm from the delivery agent informing me he was just around the corner... I tried to be calm in informing him nobody was there and my delivery time was to be no earlier than 4. In the end, CEVA had to drive to the local contractor, pick up my set, and bring it back to me to be delivered. The agent got there at about 7:30, which really wasn't a big deal that they were outside their window. The big hassle was the fact that I selected a specific time, and was told multiple times that my delivery time was different than what I chose and they would be largely unwilling to accommodate me.
TL:DR- Amazon's scheduled delivery isn't always perfect, but they'll do their best to sort it out.