[BlindHandyMan] Cutting depth per cut

[Agent086b]

  Hi all,
well have just purchased my first router and router table so will have 
many questions.
For a start.
If I wish to make a plunge cut, with say a 12 mm diameter bit. what is 
the maximum depth I should go for a first pass?
I am not sure if this is explaining myself correctly, so I will wait for 
the responses and modify the question if necessary.
Thanks as always for the great help.
Max.