That's a question we get a lot of at this time of year.Folks buying gifts on line want some assurance that their purchase will arrive before Christmas.Here are some guidelines.USPS Priority gets delivered in 2 to 3 days. If you are shipping from one coast to the other, count on three days. USPS has announced that the last day for shipping to arrive pre-Christmas is December 21. If you want to track your shipment, there is a very small surcharge for a tracking number. Insurance also can be purchased, depending n the value of the package. You still might want to purchase a tracking number, because it one is not included with insurance.UPS promises deliver in 5 to 7 days. UPS is more expensive but often a better service large or heavy packages.And, of course, there always is FedEx. FedEx will deliver overnight. But you will pay for it.