It really doesn't matter when you begin to grow just as long as it falls within the growing season. Your plants of course will not grow to their full potential, but once the outdoor light cycle changes to 12/12, they will begin budding. Take for example one of my buddies. He has five mother plants outside over five feet tall that he plans to cut hundreds of clones off of and plant a few weeks before the light cycle changes. He wants hundreds of extremely small plants spread throughout the plot that may yield only a half/O, but when you've got hundreds of them, who cares? It's all about how big you want them to be.