You need atleast OBC NCL Rank between 5-5.5k in JEE Advanced, to have fair chances in securing a seat in one of the IITs. For a OBC NCL Rank anywhere between 5-5.5k, the corresponding CRL Rank mist be anywhere between 21-23k. Hence you must target a CRL anywhere around 20k, to be on the safer side. For 20K Rank in JEE Advanced, you need to target anywhere around 25-30% of the Total Paper Score besides clearing individual subject cutoffs.

For more information about JEE Advanced Cutoffs do follow the link below

https://engineering.careers360.com/articles/jee-advanced-cutoff/amp

Secondly, there is no Percentile System in JEE Advanced like JEE Main or any sort of Home State Advantage, which should be clear to you.