Not sure if this is the correct way, but I water my adult Adeniums along with my other Fat Plants/C&S pretty much daily during the Summer. My plants are fairly pot bound, so there is little chance they stay wet for long. I also don't use plastic pots.
I treat them like Tropicals in Summer and like Succulents during the Winter. I slow down watering in the Fall and water sparingly during the Winter, then inside here in NJ.
I don't have a real regimen for fertilizing Adeniums, I just fertilize them along with everything else with a balanced fertilizer and once in a while blossom booster. But, a couple of weeks before they come inside, I add some of the Bayers Imidacloprid/fertilizer in pellet form to all my C&S, I also do that in the Spring when move them outside. That takes care of Mealies and Scale.
