What I do is get the brush wet, pour a tiny bit of toothpaste on, flatten that with another splash of water then pour the tiniest bit of turmeric on the toothpaste itself.
I start scrubbing the front of the teeth and by the time I move around my whole mouth is naturally salivated just right so I just keep brushing and then rinse.
If we tell everyone this there are companies charging hundreds for less safe ways to whiten who are going to be very very unhappy.