There are two sides to think about before you make a decision about this.
1. The GMAT is changing it's format. The format in place now is time-tested and the prep companies and books have already gotten a good look at it for a couple of years and can hence guide you well. So this is something you need to consider - do you want to keep the present format or try out the new one? (It might be well researched by the time you take the test if it's more than a few years from now)
2. As pkit pointed out, it's better to take the test closer to the time of your application since it's more recent. Unless you're a college graduate or something, in which case the adcoms might just think that you wanted to get the testing part done with when you were still in college mode.
Think about these two questions and then decide for yourself.