I didn't have a full on second outfit, but I did have an overskirt for my dress that I took off at the reception so my dress looked different.
I wore my overskirt for the first dances, dinner, cake cutting, etc. because I loved the full skirt and wanted it in photos. Then I took it off to dance and have fun! I feel like a lot of the times changes either happen before you arrive at the reception or once the dancing and partying gets going. For me, I wanted to wear the full skirt for as long as possible instead of just our 20 minute ceremony.
We escorted our guests into the reception area for cocktail hour, grabbed a drink, mingled for about 10 minutes and slipped out to change. Nobody noticed until a few minutes before we came back! They were busy drinking, nibbling, socializing, checking out our decor, signing our poster (instead of guestbook).
Hey there! Have you given this a lot more thought?
If you want your ceremony dress to be the one that is photographed, etc. then maybe after your meal, first dance and speeches would be a good time to slip away and change. What is your second dress like? Is it more of a party dress?