No problem.
We didn't get much warning prior to taking the test, so there wasn't any preparing so to speak. Although the first two semesters of Paramedic class was almost 8 months of preparation.
We thought that we were going to take the HESI right before registry, but ended up getting it about 7 weeks earlier at the beginning of our third semester of medic. I think the change in timing was for the best, because it was a good measuring stick and if the scare hadn't been put into people early in our final semester, some might have put on the cruise control and got a rude awakening at registry. Even with a passing grade, I got to see the areas where I just sqeaked by and could focus more time on those subjects.
Prepare for it like you would a final or registry, because anything could be on it. As always, start with the basics first... BSI, scene safety, A, B, C's and then go from there.
Best of luck.