I don't think I've ever heard of anyone NOT increasing volume whilst 'on'. Remember to increase calories intake as well. As this is your first cycle you'll need to 'feel' your way about a little and, of course, listen to your body.
All though you're probably not looking this far ahead at the moment but also consider your current training volume and how you will need to reduce it accordingly as you come off. This sounds obvious but it can be hard to come to terms with when it comes to the crunch, trust me.
If you post your cycle and PCT you will be offered good feedback which may be of value to you.