ya, you want to sex in most cases at the earliest point possible so that you know what you are getting into. Once you have established the sex you can grow them nice and big and green! You have a good rough plan, but I wouldn't try to map anything out this soon into the game. If there's one thing I have learned its that you can't have a set plan cause things change on relatively short notice. Like Bejay said it is probably a good idea to wait to switch to 12/12 for a week or so after transplant to give the plants time to recover.

As far as your bigger container question goes; you will only need to change pots when the plants have outgrown their existing pots not any later and not any sooner. You also want to avoid transplanting too much 2-3 times for one plant would be the max cutoff --it causes too much stress in most cases. A good way to tell if the plants need a transplant is if you see no further growth but the plants are nice and green and healthy. Once you put them into new pots you will be able to see immediate growth.