RebelWanderer
In case i am facing pacing issue due to 1st reason mentioned by you. Should i go for 2nd diagnostic test after a week or still i should wait for more time and practice again
That depends on a few things - how much else you might need to work on in Quant, and how much time you have before you take the real test.
Assuming you're not taking the real test soon (in the next 2-4 weeks), I would not suggest taking your next diagnostic until you've worked out how you'll be improving your Verbal pacing. And if you have things to work on in Quant besides pacing, you'd want to do those things before you take another diagnostic, because when you improve at Quant, your pacing will change. If you take a test before making those improvements, you won't be able to correctly interpret the pacing data you get from that test.
But if you plan to take the real test soon, you'd want to make pacing practice (and therefore official diagnostic tests) a higher priority, because it sounds like improving pacing is the single more important thing you can do to raise your score. Just how soon and how often to take tests would depend on your precise timeline.