I started preparing for the GRE in September and I am taking it the 2nd week of December. I took a mock test today (Powerprep 1) for the first time and I scored 288 (V143 and Q145). I am so disappointed and discouraged at the same time, because I have been preparing for two months and have memorized over 600 words for a score of 288. I also didn’t realize that time would be a problem for me. I ran out of time but I guessed on the remaining questions. Any tips? What should I do next ? I feel like I wasted 2 months, please help with suggestions. Thank you
Try to skip questions.Also, I would recommend that you try to have some time to review the material you studied . For eg: if you learned about some TC technique then at the end of the day , take 10 mins out to do 1 TC section of a big book test(timed) using that technique ; in this way you’ll get an understanding on how well you’re understanding of the material currently is and then you can adjust the plan according to your needs in the days going forward.
Thank you 
Perhaps you did not really waste two months, you could still have learned something. The mock test might provide some insights as to what some of your weaknesses might be. There is something more to GRE vocabulary questions than just knowing the vocabulary itself: grammar, understanding the sentence, and nuances, etc. Those are possible avenues one might explore next.
Also, it looks like someone who sticks to a preparation for two months might have fortitude. So, as per @HoldMyBeer suggestions, you might use that fortitude in a structured way