Guano before flowering and during, a lot of guano growers don't give enough...it's a thin margin of success, powerful stuff! Plus over watering can make it appear that your nutrients are to low, but you also show signs of toxicity...since it uptakes far to much water, kills roots and becomes more nutrient sensitive.
Give good light, good water, know exactly what your ppm level of nutrients are at...let the nutrient solution settle since particles can float for quite some time (hours) and then not register on an EC or ppm tester since they are not dissolved...those particles will still float into your soil and cause major problems.
Try worm tea before the guano, that can help ease you into the guano as the worm tea is gentle and a soil conditioner/root builder....almost everyone over or under doses their plants when using guano and over waters....so it has yellowing bottom leafs that seem like not enough N but then top leaf curls. I also suggest a Kelp product, as these have hormones and vitamins your not going to get from guano or worm tea. Go for all of those and your going to do well, just be careful as guano is really dosed by the milligram.
