The form in which you are taking amla(Indian gooseberry) is very important.If you are taking triphala powder, take it 2hours after the meal in the night before sleeping.If you are taking it in the form of chyawanprash , you can have it after milk and if you are taking fresh amla juice, take it empty stomach in the morning.
But never take amla powder with milk or within two hours of having milk otherwise it may lead to severe indigestion.