Now's about the time to take it, or at least prepare for it. Get an early start, because it takes time to apply to graduate schools, and you need your GRE score on hand when you apply.
The GRE won't normally make or break you, but if you do well enough on it, it could weigh in very strongly for getting fellowships and other aid. A big part of the reason I was awarded the Hertz fellowship was my GRE scores and recommendations from professors.
Have your favorite professor give you practice GREs to work on. About two practice tests will ensure you will do as well as you're gonna do, and then take the real test. Having practiced the test, you will have an idea of how well you should expect to do, and minimize the likelihood of freezing up or bombing the test for whatever other reason.
Also, at least a few days or a week before the test, go to the test site to look around, get a feel for where the buildings, rooms and parking areas are located so that this won't throw you off balance on test day. On test day, arrive early so you have time to calm down, get oriented, grab something to eat, etc. before taking the test. You don't want to get melty right before the test, and with preparation you should be able to avoid that.
At 29 you are getting a late start on a higher degree, but no matter. Someone told me that if you can get a PhD, you must. The US needs more PhDs, especially of domestic origin. Don't go into it with the expectation that your program will make you more attractive to women. By continuing school, you are deferring entry into the job market by about 5 years or however long a PhD takes, and you will also be deferring your entry into the dating market by about the same amount. Yes, I know some graduate students date, marry and even have children if they're really good at multitasking, but don't count on doing that. Looking back I can honestly say I did the best I could, and that doing my PhD was the best thing I could have done with my life for where I was at the time.
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A boy and his dog can go walking
A boy and his dog sometimes talk to each other
A boy and a dog can be happy sitting down in the woods on a log
But a dog knows his boy can go wrong
Last edited by sgrannel on 18 Dec 2008, 8:10 pm, edited 2 times in total.