watering is tough....and its especially hard to explain online via typing. plants that size in pots that big will probably need watering almost everyday. especially if you have fans blowing on them (the moving air helps evaporate water). you can buy a moisture meter raeally cheap these days to help you. in terms of yellowing flowers during flowering....a little bit is normal and it will probably gradually increase as the buds become bigger and you're further into it.