The Happy Hours are not announced in advance. You may know if there is any Happy Hour in the main page of the FUT Web App or  fifa points account cheap the consoles while it is active, or here.

The Happy Hours are more common at the end of the game. It is impossible to know when will be the next Happy Hour but they occur almost always at 6pm (UK time) and they are very common in these moments:

The staff cards are responsible to increase the consumables effect. You just need to store them in your club and the bonus is automatically assigned. The head coaches give a bonus to the training cards, the goalkeeper coaches give a bonus to fifa points account cheap  the goalkeepers training cards, the fitness coaches give a bonus to the the fitness cards, the physios give a bonus to the healing cards and the managers give a bonus to the contracts. http://www.fifaeasy.com/