Earlier quoted context omitted.
Focus less on your 'platform choice' or whatever, as that can actually be quite fluid Yeah, but programming on Windows is a PITA so I found its simpler to just eliminate that from the equation :)
And this is why your advice is actually bad, op said nothing about his platform choice and you're recommending he should go run a marathon when he's never even jogged. Windows programming is not a PITA, that's a flat out lie from you. It's total and utter nonsense, especially as Windows has arguably the best IDE of all the platforms. In the end it's exactly the same as linux programming. And iPhone programming. And B…
The OP says he wants to do a startup and plans to go to grad school for physics, but in terms of programming, he doesn't really know what he wants.
That's why he is asking for advice on what path to take -- he is asking for "preferences," recommendations, and guidance. How many startups do you know that run Windows? How many high-performance physics labs?
When people were asking for faster horses, they didn't know to ask for automobiles because they didn't know that was something to consider. The had no perspective. Helping someone onto a more productive path from the start can help them get to where they want to go faster in the long run.
How long does it take to run a marathon? The OP has a timeline of 6 months.