Well it takes them several days to process the order. If the Chinese New Year or other major holiday is in progress you need to add up to a week or two to the time it takes.
Then when shipped it take from 18 to 15 business days. EMS might be arguably faster but not by much though.
You might need to add a day or two for you there in AZ. I have a friend who lives in Tucson and it seems to take 5 extra days for everything that he gets delivered.
Sometimes orders sit in Customs for a number of extra days, it depends on what is going on in customs that day.
I have had some packages arrive 10 days after I place the order and others have taken 15 days.
So three weeks seems to be about average.