This is similar to how The Sims worked in its older iterations, with both Sims just swapping vows and smooches without anyone else getting in the way. This is fine if you're in a rush or are role-playing a shotgun wedding, but you will miss out on some good rewards if you do this.
Christine decides she wants an actual wedding. She can do this at any time with her phone, but be warned: the instant you choose to activate the wedding, the wedding will immediately take place. In previous versions of The Sims, you could plan ahead and figure out when you wanted weddings (and other social engagements) to take place. Not so with The Sims 4 Cheast: everything always happens immediately when you give the command.
Christine learns this the hard way at first. She tests out the command at night, thinking she will just plan the wedding for the next day. Unfortunately, everyone she invites is teleported to the park in the twilight, so they're starting their “party” by being extremely hungry, tired, and needing to pee.
No one is happy, and nothing has happened yet. Not a good sign since we're trying to get a solid rating for the social event.
Christine appeals to the time gods (i.e., we reload the save) and prepare a bit better. Around noon, she carefully contemplates her actions.