The urge to release the air is strong, especially if you have inhaled too much. You must, of course, inhale enough air for it to last for a long note or a phrase, but if you inhale too much you will not benefit from the extra air as the pressure from the diaphragm increases accordingly. Although inhaling a lot of air makes it easier to reach higher volumes you must be physically very strong to control the pressure of the diaphragm. Only certain Wagnerian singers benefit from filling their lungs with so much air because they wish to achieve maximum volume and they have the necessary strength to hold back/delay the exhalation. You must be aware of how much air you need and how much physical strength you have to hold the air back/delay the exhalation. You may notice different songs need different degrees of support energy. Practise breathing with the amount of air that is comfortable for you until it becomes natural.