Where in the object-oriented design process is an architecture pattern chosen?

Most object oriented analysis and design books and resources describe the process where the analysis phase is followed by identifying classes. I understand that experience will often give you an idea of which architecture (if any) you should apply but is there a specific point in the object oriented design phase where this should occur? I'm about to start a large personal project and I want to make sure my choice of architecture doesn't disregard something from the analysis phase.