Sorry I am late to the party- you may have already taken the test! If not, hope this helps:
I just took it this month. I started looking into the Barron's CCRN book 3-4 months before. I chipped away slowly by reading through the chapters and familiarizing myself with the info (taking each practice test as it came up in the book). I maybe spent 1-2ish hours a week just plugging along with the info.
At work in the little down time I had, and at home, I used the Pass the CCRN app to go through questions. I did not make it through all of them, but they were great when I didn't want to bring my Barron's book around.
About 3-4 days before the test I spent 3-6 hrs a day just taking the practice tests from the Barron's book and the online one it provides as well. Best advice is to look at the rationale as soon as you answer that question (not at the end of the test) while the info is fresh.
If you know the Barron's info well and understand the rationale for those questions as you go, you'll be solid! I found that the questions/information was very similar to those of the actual CCRN test.
Best of luck if you have yet to take it.