Background (skip this if you want): I'll obtain my master's degree in about June/2018 or so (if everything goes smoothly), and I intend to pursue a phd in the US. Thing is, I'm from a country in the south hemisphere and the academic term here is different than in the north hemisphere, and so I'm a bit paranoid with deadlines for graduate applications. Looking around at questions such as here and here, and around in some universities' sites, I understood that graduate applications are usually open from October through December, and the academic term would start around September.
Question: is there any reason why someone would want to take the GRE in April, other than if he or she were actually retaking the test trying to get a better score? I know that they keep the scores for five years. The bottom line is: I'm unsure whether I should take the GRE in April or in September. April seems too soon, the fee is expensive and I'd like to do it only once, preferably being well-prepared. I'm sorry if I'm missing something obvious or common sense, but I'd rather ask than remain ignorant. Thanks!