Hello
Since you are aiming for top schools then a score above 700 is desirable. However GMAT alone won’t determine your chances of admission; beyond the academics will also help you in determining your candidature and your work experience plays a vital role as well.
Start thinking what makes you unique and what’s that ‘hook’ that will be key to your application. Make sure you follow the ‘show rather than tell’ principle so that the admissions committee could really understand your strengths and differentiating factors Although it is not just the work experience that counts but also what you did there like-what were your achievements, what initiative you took, what changes you drove in your workplace etc. So you need to ensure that in your years of work experience you have demonstrated the skills business schools are looking for. This could still put in a strong set of essays for you.