Wow - they look pretty healthy to me. Nice job. DEFINATELY seperate the plants out into seperate pots.

Never heard of using mulch before for soil - it might work. Keep an eye on your pH and drainage - two most common problems with soils, although I doubt drainage will be a problem with mulch.

Marijuana will start to bud when the amount of daylight starts to get shorter - a sign autumn is coming. That's really the only thing that will force it to bud. When growing indoors, growers usually use a 18/6 light cycle (18 light, 6 dark), and then when they want it to bloom, they switch the light cycle to 12/12. Not entirely sure how it's going to work since you planted them in November, but then again that is the tropics - I've heard some places (few) can grow crop almost year round, if not at least two growing seasons per year.

Good luck.