I usually steam for 30mn. But I just got this gr8 hair steamer on ebay for $119 and free shipping. I would personally recommend saving and getting one. Plus by the way you described your steaming process, it sounds dangerous. I wouldn't want boiling water on me or any kind of accident involving boiling water.
There is such a great difference between a hooded bonnet and steam. I can steam every night, it feels so good.