Rudrabhishek at Kashi Vishwanath temple in Varanasi that take place during the day after the Mangala Aarti and It can be orgnased well in advance where you have to take a token a kind of permison for performing rudrabhishekam at the temple. and token depending uponn the family or couple for example if there are two married couple then they will have to take the ticket separately. .Rudrabhishekam takes place at front temple and at the end pooja offerings are poured at original shivalingam and get blessings . For performing rurdrabhishek you need to book shashtri (priest for durabhieshk) and pooja samagri(materials ) and its up to you how many priest you want to chant etc .