How much time should i avoid piano practicing if i had a hand cramp? and if i have a performance should i deny it?

More information is needed before this question can be answered-like what type of hand cramp, where was it located, how long did it last, what were you doing when the hand cramp happened, etc.? Perhaps having your primary care provider evaluate this will help to determine how long you should avoid piano playing, if at all. If the cramp did not occur when you were playing, it may be ok to play.