Choosing between Montgomery GI Bill vs Post 9-11 GI Bill and Illinois Veterans Grant?

About to leave the military and going back to Illinois. I have bought into the MGIB for $1200 and qualify for a 100% of the post 9-11 gi bill and also qualify for the Illinois Veterans Grant. I already possess a Bachelors in Finance prior to joining. My question is can you go to community college for a brokers license for example using the post 9-11 if I already possess a degree? Which of the three is the best to use first? Would it be better to use a combo of the two or use one at a time? Can you use the MGIB first for a few months, then transfer to the post 9-11? Im sure that im not the only one thats finds these options confusing being veteran in Illinois!! Please Help!!!