When Fielded Underdog Abilities

When do you check the number of dice for when fielded Underdog abilities? Does it happen as the die is being fielded or after the die has been fielded?
Example: My opponent has 1 die in the field and I have 0. I then field Black Cat-Party Hardy. Do I get to use the Underdog ability since I had fewer dice as I was fielding or do I not get to use the underdog ability since we have an even number of dice after fielding?
Example: My opponent has 1 die in the field and I have 0. I then field Black Cat-Party Hardy. Do I get to use the Underdog ability since I had fewer dice as I was fielding or do I not get to use the underdog ability since we have an even number of dice after fielding?