You'll have to ask yourself a few questions to get the best idea on timing; like, how long does the strain you're growing require to mature in flowering? (8 weeks, 10 weeks, longer?) Also, how long do you plan to veg the plants out once they've been rooted? If you'll be throwing them directly into 12/12, then ignore this question. But if you'll be growing them out some, that will need to be factored into everything as well.

After every harvest, plan on taking either rooted cuttings or grown clones and putting them into the flowering room to make up for the ones just taken down.