Hi Tian, I think you've figured it out! It doesn't really matter. This is a highly controversial yet relatively unimportant issue. I think it's often touted as a "must do" strategy -- but is it really? The LSAT is testing your ability to understand arguments and make inferences, tricks like which part to read first are immensely less important than one's ability to wield those skills.
There are definitely folks out there who swear by reading the stem first (the question), and then the stimulus (the argument). There's no problem in doing this, and if people truly find that they can orient themselves by doing that, then go ahead.
Personally, I find this issue is more of a distraction than anything else. Sometimes I'll find myself halfway through the first sentence of an argument and I think "oh, I better read the stem!", and regardless of whether I do or not, I've broken my flow. So, I decided to stop worrying and just take the test. In truth, I do generally read the stem first, but definitely not when I see that it's a long one. For example, if the question asks about what role a specific line plays, I do not read that stem. This may seem counter-intuitive, but I don't want to only focus on that line (and frankly, I find it hard to remember which line I'm looking for, or I hyper focus on looking for it), I want to do my usual thing: find the conclusion and see how the argument builds towards that. Then I figure out how that line fits in.
For me, there are two times that it's helpful to know what the question is asking. One is when it's a parallel reasoning question -- since I tend to diagram arguments more readily when I see such a question. However, it's usually quite obvious that I'm facing a parallel reasoning question because the whole question takes up so much room. The second time is when it's an inference question. Then I know not to argue with the given statements. But again, it's usually obvious that I'm dealing with such a question because there's generally no conclusion to be found -- everything is presented as premises.
The final issue I have with the idea that reading the stem first is uber-important is that it suggests that you're going to do significantly different things for different questions. Generally, your job is always the same: find the conclusion, figure out how the author attempts to reach it, note what counter premises are there, and look for assumptions. Most question types hinge on these assumptions.
So, in conclusion (here's the conclusion
), go ahead and do whatever is working for you. I think it's great that you've tried out both -- that's a smart move. This is probably not a very satisfying answer for some people reading this post -- but hopefully the emphasis on reading like a debater comes through.