As noted by iPadinCanada, Apple even displays a map showing the delivery zones during the checkout process so that customers know when their orders will arrive.
If your delivery quote reads “Delivers: March 16-March 20″, then your new iPad will deliver on March 16 in major cities and surrounding areas (zone 1). Otherwise, if you live in zone 2, your estimated delivery date is March 19, and if you live in zone 3 your estimated delivery date is March 20. Please add 1-2 additional business days for delivery of personalised products or for zones 4 or 5.The vast majority of Canada's population is included in Zone 1, meaning that early iPad orders for those customers will indeed arrive on the launch date of March 16. But for those customers located in more remote areas, their orders may not arrive until the following Monday or Tuesday, or even later in the farthest-flung areas of the country.
If your quote reads “Ships: By March 19″, this map does not apply. You will receive your new iPad within 7 days after shipping.
A similar system is in place for Australia, with the country's major cities covered by Zone 1 with March 16 delivery for early orders but outlying areas seeing delivery on the following Monday or Tuesday. New orders placed in Australia are currently scheduled to ship on March 22 as availability as tightened up following the launch of pre-orders.