As an American I think it depends on how the tea is made. I have a kettle, but I steep in a tea cup rather than another dish to wash. So by standards of decorum

As an American I think it depends on how the tea is made. I have a kettle, but I steep in a tea cup rather than another dish to wash. So by standards of decorum I put milk after the tea bags are removed. I put cream at the bottom of coffee cups before the machine puts coffee in about half the time, though. I have a lot of family in Britain.