Q.Burning bush berries
When do I plant the berries, spring or fall? Are they really poisonous to dogs and cats? Are the berries something that a dog would WANT to eat? Are they desirable for a dog? I picked some along a highway (the berries) and I want to plant them but I don’t know WHEN to plant them. And I certainly don’t want our pet dog to eat the berries and get sick or worse…would he WANT to eat the berries? And are they ALL poisonous? Thank you so much!

The burning bush is toxic to both dogs and cats so you may want to reconsider this choice.
Here is a comprehensive article on how to propagate a burning bush: https://www.gardeningknowhow.com/ornamental/shrubs/burning-bush/burning-bush-propagation.htm