Timing of procession with music

Following but there's so many factors I doubt that there's a good answer to this question. A good live musician will be able to end the song early/extend it for as long as you need. Also, a good DJ should be able to fade out recorded music and smoothly transition between songs

The song can be put on a loop if need be. When I was in a friend's wedding, she had four bridesmaids for one song. The song was a little over four minutes and she wanted the whole song to play. So we each had to walk down the aisle for a little over a minute. I would not stress about how long it should be. Everyone walks at a different pace and all this can be figured out when you have the rehersal.

There are a ton of factors in play here! How long is your aisle?

I'd just pick the song you want and practice it once at the rehearsal to see if you should loop the song or if you can time it right!

Ok thanks everyone! That helps! Does the DJ usually come to the rehearsal? He is doing our ceremony music.