Not sure you have much choice at this stage!
I've heard that rounds 3 & 4 are the most competitive, but don't let that discourage you. If you have got your GMAT out of the way (or will be ready to take it soon), and you have the time to do a good job on your essays, then you may as well apply and see how it goes.
I keep seeing comments that it's more competitive if you are Indian and come from an IT background (I don't know whether you do), but I think some weight will be given to the notion that it may be beneficial to LBS in the long term to have a disproportionate number of MBA graduates who are from (and returning to) BRIC economies.
Either way, best of luck!