Homogeneity doesnt equate to success. Saudi Arabia and Iran are also homogeneous as are many more socially and economically backward nations. I don't think that even an early POD involving Indo-Europeans would yield a homogeneous India. You would then have multiple Indo-Iranian and Tocharian nations and be like a mirror image of Europe but in the East. So you could then have conflicts inbetween the many Tocharian,Iranian and Caucasian branches. Doesn't qualify for your purpose here,IMO. You see? Someone will convert to Scythian religion,someone will convert to Tocharian B religion,some will convert to Indo-Aryan religion,some to Sogdian religion,some to Tocharian A religion,some will convert to Western Iranian religion and so on. So that's definitely not a homogeneous India except in anatomically.
From what I infer,you seem to want a Hungary model for India. Hungarians are a mix of mostly Pontic Scythians and Caucasians(Avars),Uralic Magyars and other Uralics,Slavs,Romans,Germanic since,etc. Today,they are homogeneous. This is possible very remotely. The problem is that India is too large compared to the Danube plains. This isn't impossible. But only very tricky to achieve. You need a large enough homogeneous migration and settlement which is possible only towards the Modern Eras.