This is what I've gathered from the N-L articles posted by @Seeker994 :
7:30 PM Stacy arrives at Kirby house (NL June 19). Nigel delivers cake to Suzie's.
8:00 PM Suzie arrives at Kirby house (NL June 19)
8:30 PM Party @ Joy house. The girls reportedly ask Brian if they can stay the night there. (NL June 19)
10 – 10:30 PM Suzie and Stacy reported seen at the A-Mart with another female (Janelle?). Stacy was with a man. Clerk Steve Thompson “vaguely” remembers the girls talking about meeting up later that night (NL June 19). Janelle claims they were all together the whole night (NL June 20, 21).
10:30 PM Stacy calls her mother (from the Kirby house?)
11:30 PM The girls go to the Elder party (on Hanover). (one mile from the A-Mart) (NL June 19)
2:00 AM Back to Party #1 (girls get a ride from Shane Appleby in a jeep). Joy declines invite and Janelle offers to let them stay with her. (NL June 19)
2:15 AM A woman resembling Sherrill asks A-Mart clerk Steve Thompson about Suzanne Streeter by name, and 2 other friends. (NL June 18, 19)
2:20 AM Suzie and Stacy leave the Kirby house in their own vehicles to go to Suzie's house. (NL June 19).
--------------------------------------------------------
Any corrections greatly appreciated.
I could not find if it was reported from where Stacy called her mom. 10 - 10:30 PM is the attributed time. I would trust Mrs. McCall on this one.
Possibly she did not want her mom knowing she would stay the night at a boy's house, and used Janelle instead.
It wasn't until later, around 2, when they got back to the Joy house, after the Elder party, that the girls found out that they couldn't stay there.
When did they decide not to go to Branson that night, and why?
It would seem that decision was made early, between 8 and 10 PM or so, when they asked Brian Joy if they could stay at his house, and when Stacy called her mom to let her know they would not be going to Branson that night.
Unless, of course, the NL got their times wrong...
Thanks for posting the timeline. I've been over it many times and feel the sightings at the gas station/convenience stores that night can't be ruled out. They fill in some empty spots in the timeline. JMO, its still not clear where Stacy & Susie went that night, whose cars they were in, how long they stayed at the various parties. It bolsters my theory that there were some non- high schoolers hanging around the periphery of these parties, probably selling drugs to the HS kids who were wanting to have a big time on graduation night.