When you place the iMac into the shopping cart on the Apple store it gives you an estimated building date which is currently at 1-3 days, then you have to add in the shipping time.
Whenever I have ordered any computers off the store I have always selected "Standard Freight" or whatever they call it, the one that's free

. It has always been upgraded to FedEx and it usually takes 2-3 days to get up here to Canada.
Hope this helps!