I don't understand the first question you asked about the light. Re-wording maybe?

Also how many weeks into vegitation stage do i change into flowering?
Wait at LEAST a month, but you can go longer up to years.....It's all on your really. Also, depending on your grow space you want to make sure that you are going to have the room for your plants as to when you get to flowering they are going to stretch and double to triple in size. So KEEP THAT IN MIND