I am usually involved in a few musicals at least backstage working on lighting every year, and my wife more than that.
I just finished installing a refurbished 96 channel dimmer rack into a high school theatre we work out of that we bought out of an idled City TV newsroom for a very good price It took me and others 6 thursdays in a row, and a full Saturday to bring back into service in a form to meet our needs. Others in the lighting crew installed more circuits to the lighting pipes to bring our rig up to something like more than 200 channels. Then another 4 nights to hang the lighting rig for the current production 'Urinetown'.
The company is Etobicoke Musical Productions, a west end musical company I have worked with for over 20 years.
If this is your first musical, and are still otherwise working some sort of a 9-5 job, you will soon learn why the week of rehersals before the show opens is called 'Hell Week' by many.
Hope you have a great time, both in rehearsals and with the performances.