I don't know why, but I kind of believe that GA did see them the morning of the 16th. I don't think that he's been truthful about the circumstances (just like "any other day") but I do think he saw them. Based on this belief and the pings for June 16th, I think that Caylee was killed between 2 - 4 pm on June 16th. KC then took her to the yard...placed her first, beside the pool and then moved her into the more hidden corner beside the playhouse so that she could remove the lid of the sandbox. I think she placed her in the sandbox, and put the lid back on. The 16th was a Monday. Her parents were working. CA has stated that the sandbox was not used all that often as it was messy. The weather was rainy and she knew that her parents wouldn't be fussing in the yard; let alone at the sandbox. KC left Caylee there until sometime before the weekend. I think she definitely moved Caylee before the week-end as she would have been afraid to leave her there with her parents being home all day Saturday/Sunday. If I've understood the forensics correctly, the body was in the trunk in its 2.6 day of decomposition. That would mean that KC placed Caylee there sometime between June 18 and 19th.
MOO
ETA - I also do not believe that KC EVER buried Caylee in the yard. No way. I can't imagine her digging a grave under any circumstances. The shovel was used for something else. Maybe to pry up a paver? To move or shift something but definitely not for digging!
Pinkpather, I think that you are right. No, she never buried her in the yard. She borrowed the shovel and was planning that. But, it was to much work. I think that she put her in a container or plastic trash bags until her final disposal.