considering the importance of answering first 10 questions correctly
There is no extra importance to answering the first 10 questions correctly. The earlier questions are not worth more than the later questions - that's a myth. So, first, don't worry about that at all!
When you wrote your post, you said you had 10 days left; there are only about 5 days left now. Unfortunately, it's very unusual for someone to raise their verbal (or quant) score by 5-10 points in 5 or 10 days. A 25 to 28 on verbal is 35th to 47th percentile (approx). 33 to 35 is 66th to 73rd percentile. That's a HUGE jump and would typically take more like 5-10 weeks.
I know that's not at all what you wanted to hear, but I think you're going to have to make a tough decision. You can take the test as scheduled but lower your goal score somewhat, or you can postpone your test in order to try to raise your score to your target. (You can also take the test as scheduled and just hope that something miraculous occurs - but I have to tell you that the odds aren't very good. I don't want you to have false expectations.)
If you decide to postpone the exam in order to work on raising your score, let us know. Also, let us know a lot more detail about your strengths and weaknesses across the verbal section - not just overall hit rate by question type, but accuracy by sub-categories as well (specific grammar rules, different kinds of CR and RC questions), and don't forget the timing data (again, not just overall timing data, but the time you tend to spend on different kinds of questions).
The general timing benchmarks are:
Quant:
Q10: 55 min left
Q20: 35 min left
Q30: 15 min left
Verbal:
This is trickier because it partially depends upon where the 3 or 4 RC passages begin. The below assumes that one new passage starts within each quarter of the test (Q1-10, Q11-20, Q21-30, Q31-41). You'll have to adjust accordingly. (For example, if the 2nd RC passage starts by Q10, then you should expect to have maybe 53-54 min left instead of 56.)
Q10: 56 min left
Q20: 37 min left
Q30: 19 min left