I've tweaked the timeline with a few more details...
[*] Noon (Approx) LG leaves to drive LDhummingbird, friend and verified insider, home.
http://www.websleuths.com/forums/showthread.php?p=9677907&highlight=errands#post9677907
[*] 2:00 PM (Approx) Neighbor sees Alanna playing on his front lawn with his grandchildren @ approx. 2 PM.
http://www.khou.com/news/texas-news?fId=214092951&fPath=/news/local/&fDomain=10247
[*] 2:00 PM (Approx) One WS opinion of time that the video of one of the "lingering" cars was taken
http://www.websleuths.com/forums/showpost.php?p=9688467&postcount=778
[*] Time Unkown "MM <snip> typically works from home and was home with the children and gave Alanna permission to go out and play with a specific neighbor, who was not at home."
http://www.websleuths.com/forums/showpost.php?p=9677742&postcount=888
[*]
4:00 (Approx) LG arrives home from driving friend (LDhummingbird) home. " Alanna was not at home when LG got home."
http://www.websleuths.com/forums/showpost.php?p=9677742&postcount=888 AND
http://www.websleuths.com/forums/showpost.php?p=9688489&postcount=781
[*] 4:00 - 4:30 One WS opinion of time that the video of the other of the "lingering" cars was taken
http://www.websleuths.com/forums/showpost.php?p=9688467&postcount=778
[*] "Midafternoon" First possible witness reported sighting of tarp, as per Macon description
http://www.star-telegram.com/2013/07/02/4977697/body-of-young-girl-found-in-saginaw.html
[*] 6:00 PM (Latest) " By 6 PM, Alanna's mother and older sister began looking for her."
http://www.websleuths.com/forums/showpost.php?p=9677742&postcount=888
[*] 7:00 PM Tarp spotted no later than 7:00 PM as per Macon
http://www.star-telegram.com/2013/07/02/4977697/body-of-young-girl-found-in-saginaw.html
[*] 7:15 PM (Approx) Alanna's body was found by teenagers at approx. 7:15 PM
[*] 7:33 Tarrant County Medical Examiner declares Time of Death
http://dfw.cbslocal.com/2013/07/03/body-of-murdered-saginaw-girl-identified-as-6-year-old-alanna-gallagher/
[*] 8:00 PM Tweet by Fox4 reporter ‏@Saulgarzafox4 2 Jul: Neighbor says the victim's Father knocked on his door asking if he had seen his daughter around 8pm #SaginawMurder
https://twitter.com/Saulgarzafox4
[*] 8:42 PM Sunset
http://www.websleuths.com/forums/showpost.php?p=9688853&postcount=856
[*] 9:10 PM Twilight
http://www.websleuths.com/forums/showpost.php?p=9688853&postcount=856