I went for it. My school has a stated policy that you may not apply until all prereqs have been completed, which tends to result in a semester off. However, they don't enfore that policy, I found out at a pre-nursing society meeting that the admissions director spoke at. Of course, she recommended that especially younger students might want that semester off. I brought up the accelerated program, which is what I start in June, and of course she starts to stress how terribly intense it is, and how - god forbid - you don't get summers off. I've been working for 11 years, year round, whether or not I was in school, so "summers off" is a foreign concept to me.
Are you still only 18? I'm 27, so it's really important to me not to waste any more time. Think about what else you could do this summer/next fall if you weren't taking intensive classes. Do you need to save up some money before the nursing program starts, or do you have help? Are there any trips you want to take? You might not have much time to work or travel once NS starts. What are your friends up to? Are they going to try to drag you to the beach every day, so you won't be able to motivate to study? If you're OK with missing all of that, then sign up for the summer courses that you need and apply. If that temporary C in physio drops your GPA too low and you don't get in, you're just back on your original timetable. Make sure you know when the drop deadlines are too, so if you are overwhelmed in the summer you won't be penalized. Also, I'm not familiar with your school - will you have any additional co-reqs to take once cllinicals start, or is that all finished? You may want to wait the extra semester if you still have any of those left. Just really sit down and think about it. You are only young once - I'm rushing to finish now b/c I took a few years off to play. Good luck with whatever you decide, and I'm sure you'll be fine.