passed the NCLEX in 85 I was getting 70% on U-world CAT test when I started and when I ended I was getting 80%
I suggest doing 200+ questions a day and read rationale plus Mark Klimek lecture he is amazing
I will say taking the NCLEX was similar to U-World CAT as far as set up and the more comfortable you are with CAT exams the easier you will find NCLEX - Good Luck

I also passed NCLEX-RN in 85 Questions, I started out using the test plan map where you review content in-depth with videos and answer questions only related to the video content. This would be a great option for someone starting to study 5-6months out in advance. But for me i only have 1.5 months before i took it, so i started doing the uworld CAT tests every other day, reviewing the rationales seriously and making flashcards for every missed question i got wrong. I would review the flashcards until i knew it and continued to do this up until the exam.

within the last 2 weeks of my exam i had 3 self-assessments i could use, i took one around 2 weeks out, and then the last 2 in the last week. i was getting 75-80% on the 3 self-assessments.

I also listened to Mark Klimek's lecture series 2 weeks leading up to my exam date which helped exponentially.

The flashcard feature and rationales for uworld are the best around. I couldn't imagine using any other program.