this is my opinion - GMAT-wise it's better to read the question first to have an idea what and how to attack in the argument. BUT CR Bible teaches very academic and masterpiece way of approaching reasoning section. Namely, CR Bible suggests that we read the argument first and then try to PREDICT the question and possible right answer. Not everyone can do this. I cannot do. I read the question first, then read the argument. For example, if I have inference or Must be true -question I know that everything written in the stimulus is doubtless. With assumption, strengthen and weaken class questions I opt to criticize the causal relationship, find gaps between the premises and conclusion, reveal stats/sampling errors, etc. Reading question firstly works better for me.

Not to say anything bad about any test prep company or material on the market, but the reality is there is no perfect way to approach it. You have to do the legwork yourself and discover the best methods that work for you. What works for me may or may not work for you. Experiment a little and in the end you will probably do better by incorporating the prep material into your own plan.