I see two primary issues: (1) Diver safety and (2) Diver/Photographer development.
Diver Safety - Whenever a diver adds new equipment and skills to their 'toolbox', it will initially increase their task loading on scuba dives. Increased task loading demands more concentration/focus by the diver on the new tasks. As consequence, other existing skills will be degraded unless they are are ingrained and instinctive (occur naturally without thinking). The foundational skill most impacted by task loading is 'situational awareness'; the diver's ability to monitor their air, depth, time, NDL and buddy. If using a camera causes increased task-loading, at the expense of situational awareness, then it is significantly impacting upon your safety.
There are two possible solutions to overcome this safety issue:
1) Ingrain core foundational skills first, before adding further task loading with new equipment or skills. Do a lot of dives, until everything becomes automatic. At that stage, add new stuff. Make that automatic. Add more stuff. etc etc
2) Make efficient use of the buddy system to complement/reinforce your own situational awareness, in anticipation of task loading. If you have a reliable buddy, make sure they will monitor/manage the dive.. including your gas etc. Make sure they will remind you to check, when necessary. This will be entirely dependent on the quality and reliability of the buddy you dive with. It can be considered the 'division of tasks/responsibilities within a paired team'. It should never be considered as an opportunity to abdicate those responsibilities to another person. You are still responsible for you. It's just a fail-safe in anticipation of potential human error.
Obviously, there is no reason why both solutions cannot be implemented concurrently.
When I teach photography courses, the maintenance of 'situational awareness' is one of my core themes. On a short photography 'intro' course (i.e. PADI Digital Underwater Photographer) a lot of drills and procedures can be taught, to emphasis and develop that situational awareness. These aren't on the syllabus, but IMHO are the most critical component and create the most critical outcome (i.e. a more 'aware' photographer).
Diver/Photographer Development - Using a camera, or other specialist equipment (reels, DSMBs etc) causes a distraction from the core dive management. Specifically, it can impact upon your buoyancy, trim control etc. I think there are two possible lines of thought on this:
1) That additional equipment shouldn't be used until your buoyancy/trim is perfected. Spend your initial dives focusing on perfecting those core skills without distraction. The degradation to those skills will be detrimental to any photographs you wish to take anyway. Good buoyancy/trim control is an essential component of successful underwater photography.
2) That using additional equipment may actually help you to practice and refine your core skills. Attempting underwater photography is a good catalyst for identifying deficiencies in skill and helps focus diver awareness on fine-controlled buoyancy development. Whilst using a camera will degrade your buoyancy initially, it will also help to improve your buoyancy development at a quicker pace. Anytime you stop and attempt to take a photo, you'll be conscious of your buoyancy - and that means you're likely to start improving it. In short - taking photographs is a great buoyancy exercise.
Thus, your choice, in respect of development, is really going to be determined by your expectations. A new diver with a camera is unlikely to get amazing photographs. Do you isolate skills first; developing buoyancy, trim etc before adding a camera? Or do you add a camera and then use it as a catalyst for all-round development. Is it better to hold-off on taking photographs until you'll get decent results... or is it better to accept sloppy results as an inevitability in the learning process?
Personally, I don't think it matters - as long as the safety issues are dealt with.
Adding a camera early in the development process means that you'll get some extra enjoyment from the dives, providing you can accept the frustration that your results won't be perfect at first. You'll also have a photographic record of those early dives, if blurry. However, if you do so, then you must recognize that the core scuba skills (buoyancy etc) are a key component to your photographic results - and make sure that these skills form a dedicated part of your self-development. The only major developmental drawback would occur if you allowed the use of a camera to distract you from your core development - focusing too much on the camera, rather than the scuba competence that actually under-pins good photography.