Id suggest starting another Qbank like USMLERx and do it subject/system wise.
While you don't want to wait too late before starting UWorld, you don't want to start before you've got a decent base. The questions of UWorld are designed to make you think across multiple disciplines, integrate concepts, and apply whatever knowledge you have. It'll be a waste of going through those questions when you don't have a good enough background to work on.
Start with World 4-5 months out, and take an NBME before you start to set a benchmark.
