Homilies are a funny thing. At least this has been my experience. They kinda have a life of their own and don't take to being "managed" very easily. For me, each homily is a unique thing - like an ill trained dog.
The first acquaintance with a new homily is usually during a holy hour on Tuesday. The Scriptures are read and rough ideas start forming. But more likely than not, there is no prodding it along on my schedule. For the first part of the week or more it is like walking Sebastian when all he is interested is smelling things and paying attention to things going in the other direction.
Then something will hit. This week it was seeing a Druher drawing of Hercules in the wilderness kicking it up with the ladies Vice and Virtue. Then things start taking off as ideas race around my head.
I think I know where it is going but I am often wrong. I've heard people who write books talk about this. "All of sudden my characters start saying and doing things all on their own." I think I see a clear highway ahead but who knows where the homily is going at that point.