My first year in graduate school was definitely a big jump from undergrad. And one of the most important decisions I had to make was where I was going to study. Many times I would try to sit where other graduate students from my department studied and I would find myself talking more than working. Alternatively, whenever I stayed at home I would find too many excuses to be distracted and it limited the amount of work I could accomplish. So I eventually came to understand that when I studied at the library in the graduate commons, I was able to focus more and get more done.
The Graduate Commons are located on the 8th floor of the East Tower in Herman B. Wells (Or just Wells) Library. The great aspects of the Graduate Commons are that 1) You need to slide a graduate student ID through the card reader in order to gain entry and 2) It is a quiet environment so whenever people talk other graduate students will simply give a glance and it serves to keep the area quiet. By the way they are remodeling parts of Wells and it is amazing. There are also a variety of other libraries on campus that are open until different times so look at what works best for you.
In addition to all of our great libraries there are coffee shops around the campus. Make sure wherever you like has a reasonable amount of outlets to plug in your computer. The great thing about Starbucks by the sample gates is that it is open until midnight most nights which is were I am typing as we speak Not advocating either way, just informing.
And when you think about when you work best, some graduate students in my cohort work best from 12pm-3 am. Other students treat graduate school like a job, not only in terms of how hard they work, but also in the sense that they only work from 8am-4pm. Others works differently on different days depending on the workload for the week. So there is no right or uniform way, but rather you must find what works for you and stick to it.
So testing out where you work best, during what times you work best, will seriously pay off over your duration in graduate school.