When do you light a memory candle?

I don't think I've actually seen anyone use a memory candle before and I have been thinking it might be nice to have one for my dad who passed away last year. I am also doing a unity candle but guess that is separate and both of our mothers will light that. I do not want to call a lot of attention to the memory candle because it hasn't been that long since my father passed away and I'm already afraid that I'm going to have a rough time that day. My uncle is walking me down the aisle but I was thinking maybe my mother and I could light it and have something about that in the program? Or maybe my sisters, who are both bridesmaids, could do it once they get to the altar. I thought with either option nothing would be said about it vocally, other than a small mention in the program.

How are these traditionally handled?

At a friends wedding the paster welcomed everyone and talked a little bit about the couple, then they played a song and that's when the memory candles were lit. The brides mom passed away so she stood with her aunt at one candle facing the guests and the grooms mother passed away, so he and his father stood at another candle facing the guests. The stood there the entire song.

There was not a dry eye in the entire church.......