So I can (somewhat) relate to what you're currently experiencing. My school only gives like 3 weeks off in between 2nd and 3rd year for us to take our test, which unfortunately means we don't really have a "dedicated" period of study time. I know some individuals in my class started using uworld back in December or January, but for me I only personally started using it a month and a half ago.
It really depends on your study style; for me, I felt like I really needed to get a good grasp on the material before I even considered doing questions about things I've never seen, so in that respect I'm glad I waited, and I believe that reflects well in my actual percentage on the qbank. Now, that doesn't mean I'm doing it the "right way" or anything like that, everyone learns differently. I can see the benefit of doing the qbank early and maximizing your chance of retaining all of that knowledge vs starting/finishing closer to the test and risk some info slipping out of your brain.
Again, I don't really believe there is a right way. But for me, using a different qbank along with classes during the year (in subject) and saving uworld (timed random) for "dedicated" or the last few months before your test has been a good strategy for me.
