Hello Shreyas,

You can not apply for JEE Advanced after qualify JEE Main Paper II. If you wish to get admission in IITs for B.Arch programme, You need to appear JEE Main Paper I not Paper II. Paper II of JEE Main is only for the admission to NITs and CFTIs. You need to qualify in JEE Main paper I & JEE Advanced after that you have to register for JEE Advanced AAT, which is the entry test for the admission to B.Arch programmes at IIT Kahragpur and IIT Roorkee.

Good Luck!