LLSST3

I'm a junior earning an undergraduate degree in psychology. I plan on going to graduate school for occupational therapy. However, I would like to take a year between undergraduate and graduate school. The reason is that I would like to volunteer for a year in South America. I would be teaching at an orphanage as well as working in the rehabilitation wing of a hospital. The dilemma I have is that I want to make sure I will have a program to come back to. There would be very limited internet while I was abroad and I would not have a cell phone. I've been trying to do some research and have been coming up short. Are there graduate schools who would accept me and then allow me to defer the acceptance a year? Or would it just be possible to apply a year early? I'm not even sure if this is a possibility, but I want this to work out. I don't want to wait until after graduate school to go abroad because I am afraid I'll never end up going. Thanks in advance!