I agree with Harro10 (and lots of others who have followed)...you may be well advised to hire your own private DM to dive with you. Then it won't matter much which op you end up with. As a brand new diver, I would not be focussing my skills and attention on sending up your own SMB (which has its own intricacies in a current that you won't experience in the bottom of a pool), especially if you don't have buoyancy control mastered. If you ask, that private DM will probably teach you how to deploy one if s/he thinks you are doing well enough. A bit of personal attention will go a long way to helping you become more skilled and ready to join with more experienced divers when you feel you are ready. Remember that in Cozumel you are diving in current and that is a game changer in terms of having a DM at your side, ready to assist you if you need it, while still guiding the rest of their group.