One thing all the veteran growers will tell you, in soil let the plant tell you when its time to start feeding, that 4 weeks in a 5 gallon pot is an "average", could be 3 weeks could be 5 weeks. Different strains use up different nutes at different rates.
3/4 tsp=3.6ml@1/4 strength your talking about the Grow Big and Big Bloom, less the Tiger Bloom.