Plans to split the initial 20-minute session around the streets of Monte-Carlo have been quashed, which means there may be all 24 cars on track at the same time struggling to get in a clean lap.
Many drivers have expressed concern about the chaos that could ensue given how slow Formula One newcomers Virgin, Lotus and Hispania Racing have proven to be.
It has been worked out if every car is on the two-mile track, which takes 75 seconds to lap, each one would be just three seconds apart.
Asked if Red Bull would be first out of the garage on Saturday at the start of qualifying to ensure track position, Horner joked: "I think we'll be camped down there on Friday night!"
Horner concedes the first qualifying period is "the most worrying aspect", and added: "It's about getting a lap that is sufficiently clear to post a time to get through.
"Unfortunately, in terms of statistics, there will be a car every 140 meters if they all run, and there's obviously a big difference in pace between the cars.
"The worst thing will be when you come round into Rascasse every lap and there is a queue of five cars.
"One way of looking at it is maybe you run for the full 20 minutes in the hope of getting a clear run.
"Or you pick your gap when the slower teams have pitted, so making sure you get in the one lap you need.
"Flexibility is going to be the key because theoretically the top teams only have to beat one other quick car to get through to Q2.
"But then if you look back 15 years ago we had around 26 cars for qualifying.
"So it's a matter of working with the pit crew, the engineers, to find a bit of track space and get one clear lap. That's all we need."