The way you should act is relatively simple: If it's written down in the SOP, then there is no discussion, do it this way.
If it is something not written down, then you can do it eighter way, and I as a captain should not interfere.
In practical terms it's sometimes hard not to say anything, but as long as it's safe and reasonable economic, you can let the other pilot let make the "mistake".
If I see that the other guy's doing it over and over and not learning it, then you might give him a hint.
Dani