Indian English is closer to British English than American English, so if you specifically want it to be in Indian English but don’t know that yourself, I’d use British English.
But unless you have some special reason to believe that it’s important, I don’t think it really matters. All of the forms are pretty understandable by everyone else. I can tell that someone using British English isn’t from here in the US, but it’s not really an understandability problem. Long term, my guess is that they’ll just blend together due to international interchange anyway.
Maybe if you’re a professional journalist in the US and the publication you work at has specified American English in their style guide, they might care about your ability to specifically do that, but I can’t believe that there are many positions that would. I’ve worked with people who use British English on the job in the US.
The only specifically-Indian English word that isn’t present in other forms of English that I can think of off the top of my head is “prepone” – that is, to move to an earlier time. It’s a riff off “postpone”, to move to a later time.