Article: If your party starts at 7:00pm, have all the guests be there by 6:00pm. People are always late to parties, this way, everyone will be together by 6:30pm and you'll have plenty of time to organize the big reveal. You'll have a few people who are actually punctual. For them, make sure you have some food and drinks ready on time so they're not left bored and hungry. This is why having their best friend helping you out will be a life saver. They can have the person with them, going and doing whatever the cover plan was, and you can correspond with them – they should let you know when they're on their way, etc. You can then manage the party and the guests. Make sure they keep you posted on how things are going and how far away they are. This way when you get a text that says, "10 minutes!" you'll be fully prepared. Some people choose to go with the standard lights off, hide-behind-couches, yell "Surprise" or cheer surprise. Other people choose to pretend it's just a normal party and let the person find out when they see their name on the cake. However you choose, be sure all the guests are on the same page. You may want to practice before the surprise. Make sure all the logistics are covered. Can your friend get in? Make sure the door is unlocked so you don't have to ruin it by coming to the door in a dark room. Will parking be an issue? Is anyone in the bathroom as the party person is walking up the stairs? Get them out! And success! Your well-planned party has gone off without a hitch! Well, hopefully. Did they have any idea? Even if they did, they'll feel incredibly loved and appreciate all the work you went to.

What is a summary?
Have everyone arrive an hour early to the party. Have one person with the guest of honor as the "Chaperone" to distract the guest of honor and one person with all the attendees. Make sure everyone understands the big reveal. Surprise them!