I started 40s-50s on UWorld and ended up around 70s after just one month of dedicated.... I got what was a respectable score in my day... I barely made one pass through UWorld.
I believe the equivalent of a 170s-180s on a diagnostic to 220s one month later. I studied about 8-10 hours a day for mostly 6 days a week for 4-6 weeks IIRC. Nothing back breaking.
I'm two things, a huge slacker and fairly good at multiple choice to make up for it.
I think if you're nothing like me and you actually tried hard during medical school, starting 40s-50s in UWorld is average and 2-3 months is PLENTY for getting a decent score. I'm not good at advice meant for high achievers though, sorry.
It has been a while since I took it too, of course.