Altenating nodes is also a sign of a female in my experience from grows. You do not have to wait until the sixth nodes appear either. Some plants grow slower or fatser then another. One might have six nodes at 3 weeks and some might not be out of seedling stage on the 3rd week. Some plants Mature faster, some Slower. The height of the plant when you deceide to flower it will determine the final height. This is mostly predetermined by strain, but light also plays an intricate part. I do agree one should wait to see the two stamens or preflowers on the sides of the nodes before flowering. It will cause stress if 12/12 from the jump. That is just lame to me. I like to veg under a MH, then I swap to HPS to flower. It works the best. Although I do have a homie that has recently added some T5's to his veg room and I am pleasantly surprised by the increase in vegative growth. Cudos to the T5. Your plant is ready to flower now, but I would give it a few weeks to let the PH adjust for optimal flowering. Hope this helps...1ne Love