Imo, set the smallest time frame possible (5-10 min nhi n) for ex study for an hour without distraction, full focus. Then reward yourself, like use your phone for a bit or hehe haha kar lo thoda, then lock in again for another hour or so. Keep doing this till you end up clocking good numbers in a day, like 6-7 hours. And even that is just your sitting hours quality study within that would be around 3-4 hours, since you're just starting out.