I started working full-time almost a year ago and I make around Rs 3.5 lakh. A $100k dollar salary in US is equivalent to around Rs 10-12 Lakh in India. Realistically speaking, How long will it take before I can to get somewhere close to that number ?

how should we know?

but probably by not working for clients in india?

You probably can't without jumping the pond and coming back as senior Management. Or you can just wait til everyone in your reporting hierarchy dies and then you are Sahib 😋

You'll never make that as a dev though, you guys treat engineering as entry level grunt work on the payscales.

Given right skills and right opportunity, You could earn that much anytime I say. There are many companies in India who would pay that kind of money even for a starter.