Passing through Copenhagen
 

So, my family and I will be traveling this summer time Ireland.
One flight option includes an overnight layover in Copenhagen. How long after we land could we expect to be out of the airport? How soon the next day would we need to be back?
This our first international flight. Just trying to anticipate the best we can.

A lot of missing info.
Which day of the week are you talking about?
What times of the day are you looking at?
Do you have checked luggage you have to wait to retrieve?
Which leg are you doing the CPH layover; from wherever you are to Ireland or from Ireland to wherever you are heading to? Departure process time depends on the destination. Airline sites usually have boiler plate recommended airport arrival time listings.