you cant use that phrase for the future, only the past or present. So you can't use it to say that doing something now will result in the chickens coming home to roost. You use it when bad things happen to someone and you can trace the problem back to something that they have done. So like, He was so mean to his co workers that when the company was considered firing him the chickens came home to roost and no one spoke up to say anything good to help him. He got fired as a result.
Graylits phrase "you reap what you sow" can be used for future things.
neither one can be used in a good way.