There are two questions here. One is about a surprise round, and the other is about being flat-footed.
The Rules As Written say:
When a combat starts, if you are not aware of your opponents and they are aware of you, you’re surprised.
In this scenario, you are arguing with a wizard and therefore are aware of the wizard. If the only participants in the scene are you and the wizard, it is not possible for you to be surprised.
Some DMs might rule that you can still be surprised if you are aware of the wizard but not aware that the wizard is a potential enemy, but that is a house rule. (The link provided by KRyan's answer has some more discussion of this.)
Using moment of perfect mind is an immediate action, and the rules for immediate actions say:
You also cannot use an immediate action if you are flat-footed.
So: if the wizard wants to spellcast at you, then the two of you roll initiative, and if the wizard beats your initiative then you cannot use this discipline.