At two years, you will be just scratching the surface of what you can learn and do in an ICU setting. At two years, you are just barely eligible to be sitting for national certifications in your specialty that are a lot harder than any test you will take in school, including NCLEX. If you really want to get a good base for CRNA school, give yourself at least 5 years in a good ICU and know your craft (nursing) well. I'm not talking about an "i'll have to look it up" type of answer when someone asks you a question, I'm talking a complete answer and then some off of the top of your head. No, you will not be able to do that for every situation that comes up but if you can rattle off answers like that for the most common, most critical situations, then you will be sitting in a good place. Just remember that takes time. The better bedside nurse you are, the better advanced practitoner you will be.