It is best to apply when your confident of your application. In R1 you may have some advantage but if you're not fully satisfied with your essays, it might be worthwhile applying in R2. Till last year, the no. of students accepted in both rounds was almost the same. That said, considering you're an Indian, it makes sense not to apply post R2 since after that only few seats are left.
I am not sure whether this would help, but I applied in R2 and received an admit.
AppMentor - accepted students' advice