Pharmacology - Approx. How long after oral administration before the biotransformation to morphine?

[PsychoActivist]

So yeh, SWIM was just curious, from what he has read, a biotransformation occurs in the liver in which a certain % of Codeine is converted into Morphine ( I guess cause it's more lipid soluable?)
SWIM was curious if anyone knew how long after oral administration it took place. Is it a continious process that happens over the course of a few hours or does it begin as soon as the liver begins to metabolize it.

In short SWIM had some Pod Tea earlier (the question is only really codeine related that's why he posted here) and he plans on taking 1mg of Alprazolam shortly. He knows GFJ and Cimetidine work to potentiate Benzo's in the same way they do Opiates so he wanted to take a Cimetidine before the Alprazolam but he does not want to interfere with the biotransformation and he is afraid of the Cimetidine occupying the enzymes in the liver where the biotransformation occurs.