When I was a senior (4th year) in nursing school, it was also my plan to go to CRNA school afterwards. So as an undergrad, it's definitely helps that you have good grades in all your science courses and graduate with a high GPA as possible. Although most CRNA schools/programs only require 3.0 minimum GPA, a lot of applicants have a much higher GPA. I graduated with my BSN-RN, passed the NCLEX, and went straight to the ICU as a new grad. Before I thought I wanted to apply to CRNA school with 1 year of ICU experience aka "the minimum". But there was still so much to learn as a new nurse that I decided not to apply after just 1 year. Instead, I decided to take some graduate-level courses and study for the CCRN within the next year. After 2.5 years later, I felt more confident and "ready" to apply. It also made my application look better since I had 2.5-3 years of ICU experience, CCRN Certification, took graduate-level courses, and shadowed a CRNA.
So I guess what I'm trying to say is, even though you may feel now that you want to start CRNA school as soon as possible, you might feel differently about doing just the "minimum" when you actually start to work as a RN. But I always kept CRNA school in my mind and always worked towards that goal. Good luck!!!