i have not completed my syllabus yet , should i start giving mock?

Now is the time. Don't wait to complete the whole syllabus; if you have covered at least 40% of it, start with the mocks.

yes, carry on with syllabus completion + start giving mocks. only focus on whatever topics you are most comfortable with right now, solve them only. Score doesnt matter, you need to train yourself for mock strategy

Try to grasp concept and practice ... mocks can be a good way but without u knowing any concept u won't be able to solve ques .
so better Get around 50% syllabus done and then only give mocks