Courtney phoned the electrical contractors who were working at the Lake Washington Blvd property, and instructed them to start work on the lights and motion detector on the greenhouse.
Tom Grant's explanation

According to Heavier than Heaven that morning, Jessica Hopper called a cab which took her to the airport after being confined to Cali’s bedroom with illness.
Cali was seen coming and going from the property, as well as electrical contractors surveying the house.

That afternoon Grant volunteers to go to Seattle and search for Kurt, it was only now he was informed Kurt was seen in Seattle on April 2nd. One of Courtney’s friends present asks, “Why don’t you go up there, Courtney?” – “I can’t. I have business I have to take care of here,” Courtney replied. Rosemary Carroll later confirmed Courtney had no official business in LA at that time; Geographical distancing from the scene? It's the perfect alibi.

11:30pm, Grant picked up Dylan Carlson at his apartment; they go to a café where they planned a strategy for locating Kurt while they ate. Together they checked Caitlin Moore’s apartment on Capitol Hill, the Marco Polo, the Seattle Inn, and the Crest; hotels on the Aurora strip where Kurt had been known to frequent. Tom Grant's explanation

Sometime during this day Cali phoned Dylan asking if he’d seen Kurt…