The first dance is the moment the wedding becomes the marriage. Everyone watches. The song you choose becomes the song you hear for the rest of your life. A custom first dance song means the song that plays at THAT moment is one nobody else has ever danced to — it's yours, written for the two of you.
What this kind of song holds
A first dance song holds the way you got here. The meeting, the first year, the decision to do this. It holds the room you'll dance in. It holds the cohort watching. The best ones use one specific detail (where you met, what you said the first time, the inside joke) to make the song unmistakably yours.
What to put in the intake
Tell us how you met. Tell us the moment you both knew. Tell us the inside line nobody else would catch. Tell us whether you want it tender, witty, anthemic, hymn-like. The song lands hardest when the specific thing only the two of you would notice is the song's spine.