Tour info usually starts trickling out in February and tickets for the earliest dates usually go on sale in February or March. So, if you want to buy them as Christmas presents, you're going to have to give an IOU. If you want to give cool Jimmy Buffett/Parrothead gifts, you could always check out http://www.margaritaville.com/ and check out the merchandise.
"A positive attitude may not solve all your problems, but it will annoy enough people to make it worth the effort." - Herm Albright