Hi Henry, the answer is yes and no . You should book any shore excursions you have your heart set on as soon as they're posted on your cruise line's site. If you change your mind there's time to cancel once you board. The cancellation times will be on your tour ticket. Generally, it's 24 hours before the tour. (A very few tours can't be cancelled, but that will be stated in the tour description.)
No, because you don't need your TA to book them . You can book them yourself whenever you feel like it.
You can wait until you board, but some tours will be filled by then.
Have a wonderful cruise,
"A truly happy person is one who can enjoy the scenery on a detour."
Carnival Inspiration 2002 Carnival Elation 2004
Grand Princess 2004 NCL Sun 2005
Sun Princess 2006 NCL Dream 2007
Caribbean Princess 2007 NCL Dawn 2008
Island Princess 2008 Island Princess 2009
Golden Princess 2009 Carnival Conquest 2010
Grand Princess 2010 Island Princess 2011
Grand Princess 2011 Carnival Magic 2012
Carnival Dream 2012 Island Princess 2013
Carnival Magic 2013 Carnival Legend 2014
We always book thru the cruise line on our first visit to a port. On second and subsequent visits, when you know the “lay of the land”, it’s then safer to arrange your own shore trips.
2005 Panama Canal
2006 W. Caribbean
2007 E. Caribbean
2007 N. Atlantic
2008 S. America
2009 Grand Voyage
2010 N. Atlantic
2011 Grand Voyage
2013 Hawaii - S. Pacific
Henry, being that you are still a cruise newbie, it would probably be best for you to book your shore excursions thru the cruiseline, unless you are familiar with the island., go to your cruise lines web site and surf around the shore excursions until you find something that makes you go hmmm that sound like fun, then post a question over on our shore excursion board where you will get tons of information