A common question I get is "When should I book my trip?" Generally speaking, the earlier the better, but it depends. Cruise lines and land tours publish their best rates months and even years out and offer early bird discounts and other incentives.  Booking early will give you the best choices of itineraries, dates, cabins, etc. 

So why does it depend? Earlier is always better on cruise lines and land tours that have no cancellation fees because there is no risk. On ocean cruises, if rates go down before final payment, the booking can usually be modified to the new rate (which isn't always better when you add in the early bird bonuses). Ocean cruise rates do go down if the ship is not filling up, but I've never seen land tour or river cruise rates drop, but it could happen. 

If you are booking a cruise or land tour that has cancellation fees, book as early as possible to get access to the best rates and options. But be certain this is the trip you want so you don't lose your deposit or incur fees.  You may be able to apply the deposit to another trip, but not always. Some river lines don't allow changes once booked. 

On bigger ships where there are more cabins to sell, you may see flash sales after final payments are due, closer in to the sailing.  If you don't care when or where you go, or where you are on the ship, you may find some good values.  Any type of "sale" - ocean, river, or land -  is based on too much availability, and that's why there are incentives that are good only on select dates. Are theses sales a good opportunity?  It all comes down to what you are looking for. 

Here are a few more reasons why smart travelers book their travels early: 
On a trip you can cancel, there is little to no risk because deposits are generally small and often fully refundable up until final payment is due. 

Early booking discounts or incentives are generally the best promotions you will see during the season.  Lock them in!  Grab the lower price and/or added amenities while inventory is available.  As demand goes up,  guaranteed rates increase and added amenities get fewer.  If there is a rate reduction below what you paid for the identical service, some type of adjustment is usually honored. 

Waiting to book your trip usually means spending more.  Of course, you may be able to snag a last minute sale every once in a while, but more often than not, pricing is higher than what it was had you booked early. And if you have to fly to the  destination, any savings will be eaten up  by higher airfare. 

The earlier you book, the better choices you have.  You'll find better itineraries, better dates, and a better choice of accommodations. This is especially true if you want a specific type of cabin, such as a suite, or adjoining or single occupancy cabins. On big ships, small ships, and land tours, popular itineraries sell out in weeks, not months. Transatlantic cruises are also fast sellers. As the ships begin to fill, cabins going for less than $3000 can be waitlisted for over $8000. Other things that sell out early are properties having fewer than 10-12 rooms, and African safaris which need to be booked 12-18 months in advance. 

Don't delay on a booking. It's never too early put down that deposit for your dream vacation. Booking early gives you more time to pay and more time to dream about your trip.