I have a gmat score of 690 (45 Q 40 V)3 years of exp in consulting,what are my chances with top20 business schools

Your verbal is ok, not great, but ok, and your quant is low. You’ve only mentioned 3 years of consulting, but there’s a huge difference between McKinsey/Bain, Deloitte/Kurt Salmon, and small industry shops.

Assuming you’re somewhere middle of the road, you’ll get in somewhere top 20 if you put together a solid package.

Almost everyone thinks they have great recs lined up . . . you may not. Remember that your bosses probably have to write letters of support for multiple people or have written many letters over the 10-15 years of their careers thus far. So, how do you rank? If you’re top 10% of the kids they’ve seen, you’re fine. Top 20%, ok. Not top 20%, ask someone else.

There’s no harm asking your potential letter writers how they would rate you. Honesty could be what saves your overall application.

Good luck,
Kate