Yea , HPS is perfect for flowering , it gives off a better red spectrum , it also has a little blue making it perfect. What i did when I wanted to start budding was basically just turn the lights to 13/11 and force em to start budding , after 3 months of vegging, so for me half were about 3 feet tall the rest 2 feet and i was just ready to start budding, within a week I knew which were males , 60% were females so I was happy , im 4 weeks in now and theyre lookin sexy , just dont start flowering till theyre atleast a foot id say