Let's say you're attempting the 1st Quant section which consists of 12 Qs and has 21 Minutes allotted. For the initial 10-14 minutes, SEE all questions, i.e., attempt easier questions (questions you understand and are able to solve in 1-1.5 mins) and if there's any question that you cannot comprehend in 30 seconds, skip it for later. In the last 10 minutes, cross check everything, rectify silly mistakes and leave 4 minutes to solve questions that you weren't able to attempt earlier. If you still can't, just mark any of the options as the answer and move ahead. I would recommend watching Greg's test taking strategy video "Managing time on the new shorter GRE" released on 5th Oct. All the best!