Hi Mike,
I would say you just should wait until you are very comfortable with buoyancy. Depending on people it may take more or less dives. A camera will throw off your balance and you will have to adjust again once you dive with one. If you are an experienced diver it will be "easy" task, if you are not, it will lead to unnecessary stress under water. Also, with little experience you might overlook simple safety rules, leading to possible injury.
The idea of taking photographs is that:
you know what you are looking for
you know a little bit about photography
you have great respect for nature and the underwater world in general
If you think you can do it, I would recommend you to start with a compact camera so that it does not disturb you too much. If you really like it and decide to upgrade to a more sophisticated camera gear, it is a great idea to get practice dives before heading to the reef.
Ultimately, there are many divers sharing their images on the web. During your dive trips you can be assured there will be at least one photographer around and you could get your images from them.
I love taking pictures underwater however, I also make a point to dive without my camera. If you are always with the camera you do tend to forget to look at the picture and can miss out. Both ways are a great experience; it is however up to you to make it a great experience and take your responsibilities. First and foremost, do not damage anything & respect the fragile underwater world. Once that simple but difficult skill is 2nd nature you are free to do as you please.
Last but not least, photographers who damage the reef, stir up sand, monopolize a subject while a few other divers would like to see it will eventually end up having a not so nice experience with fellow divers. Let's not be one them