You really have a lot to learn, dude.
A GMAT score of any level is never a shoe-in ANYWHERE. They look at your entire application, which includes work experience, your essays, recs, etc. A GMAT score can not get you in, but it can keep you out.
It's damn near impossible to get an 800 on the GMAT. Extremely rare that people do. Two years of studying for the GMAT won't get you an 800, but it will burn you out. People who get 780+ don't get those scores from intense studying; they get them because of an innate ability, the math skills of a math major, and the verbal skills of an English major.
Top 10s will take students who have as little as 2 years' experience, but that really is a minimum - 3 or 4 is even better.
Do more research about the process, and be more realistic about it. By all means set your sights high, but you clearly don't understand the process and what's truly important yet, and if you apply without that understanding, your chance for getting admission is going to be much lower.