Young and Determined: ADVICE Please

I'm currently in my sophomore year of college with a major in Nursing and I'm coming up on my second semester. Before I can really dive into my courses for Nursing, I just have to finish up 3 of my major science courses; Microbiology, Physiology, and Human Anatomy. I was advised to not take all 3 at the same time of course, so I'm taking Human Anatomy next semester which will leave Physiology and Micro for either the summer or next Fall. I really am confused as to when I will be able to take the HESI A2 Exam. I know it's best to have all of the major courses taken and completed, but I plan on taking either Micro or Physiology over the summer then only have one left for next year. When should I try taking the Exam? I'm looking to being preparing for it here pretty soon. Any advice and opinions is greatly appreciated!

P.S. I've also ready some posts about it being difficult to find a job after school, I was thinking about doing an Internship so that way I could have some sort of help in finding a job but I don't really know when exactly I should do that.