How long does it take a bride to walk down the aisle?

This is going to be different for literally every single person. It depends on the length of the aisle, how fast you walk, how tall you are, if someone is walking you down the aisle, how fast they walk, etc. Are you going to start walking down the aisle the second the song starts or are you going to wait for a certain part of the song? There's really no way for us to know how long it's going to take you. Talk to your DJ about your concerns and they will find a way around it.

If you’re Kate Middleton, four minutes. The only way to know is to go to your venue and try it, even if it’s just with the song playing on your phone so you get an idea.

I would just try it at home. find out how long your aisle is and practice walking, fairly slowly and time it. Probably 48 seconds is plenty to go 20 or 30 feet, that is almost a minute, which is way longer than it sounds. If you're unsure, loop it to be safe. Or, just loop it anyways.