Hey Growmie,
No, she hasn't started to bloom yet but she is showing sex," It's a Girl". Lol. As fas as when to change the light period, Ideally, you want the plants to finish at approximately 24 to 36 inches tall, so you will induce flowering when plants are approximately 12 to 18 inches tall, and yes you should continue with Cal-Mag during Bloom. Hopefully, I answered your question and remember Happy Growing and Free your mind one puff at a time.