Depending on how strong a flier she is, I would start with 4 and give her a test flight.

Please don't take offense at what I'm about to say, as this is not a lesson you want to learn the hard way. Dogs are predators; birds are prey. Be very, very, very careful whenever your bird is around your dog. If the dog seems to ignore the bird, it may not always be that way and one quick snap could mean the end of your bird. I have a Cairn Terrier who, for all intents and purposes, ignores my birds. However, all are in their cages if I'm not home. She's a very sweet natured dog but I don't trust her as far as I can throw her when it comes to my birds.