5 months prep

Hey everyone I am new the forum but I have been reading on the site for awhile. Anyway I took the SAT back in high school and scored a low 1100, although I didn't prepare whatsoever. I took a course at my local library for 50 bucks it was four sessions in total each lasting three hours. In high school I had an 88 overall average and got into SUNY Albany. I never applied myself in high school, I would basically look at the book but never actually took in any of the material. My first year was rough and I got a 1.93 and a 2.5 the second semester. Since then I haven't gotten below a 3.83 in the past two years and have gotten an A in every upper level economics class. I don't think I knew how to learn in high school if that makes sense. Now I am able to go into every class and figure out a way to succeed. Anyway I am still kind of worried because of how I did on the SAT years ago but I am willing to do everything I can over the next five months to hit a 600-650 on the GMAT. The question I have is, is it possible to not necessarily score well on the SAT (because I didn't prepare) and then do well on the GMAT?