Ear Cropping

I'm thinking there is a timeframe for this.  If so, what is it?  Sadie's been having alot of problems with her ears, and I've read alot of the pros and cons, but I wondering if it's still an option since she'll be 1 this month.  Her darn ears are huge (aka Dumbo).  Personally, I don't think her big ears are helping with the yeast problems we're having.  The first thing the vet suggested minus the medicine was to flip her ears back to allow some airflow.