Routing with range values

Hi

I want to index 30 days of data, in each day i will get GB's of data
I Have 30 days of data, i have 10 shards, i want to route in such away , that first 3 days of data should go to first shard, next 3 days of data should go to next shard ..etc

I am routing with date field, but i found data belongs to 1, 10,17 is going to 1 st 2, 11, .. going to next shard...etc . 

Looking for u r response
