How much percentage do you think i would need to enter harvard university ?

There is no way to tell since just about all Harvard admissions have very high GPA's and the school emphasizes other factors./

Nothing you do before high school counts for colleges. Everyone applying to Harvard has the highest grades in the hardest classes and very high test scores, and Harvard took about 6% of applicants last year. They ask for unweighted GPA, not percentages, and there's no direct conversion. They turn down thousands of 4.0 students and valedictorians every year. You need all that, and then you need a lot more - something that makes you stand out, that's related to the field you plan to major in, and a good reason to attend Harvard in the first place, which most applicants don't have. Nothing you said would get you in.