In reviewing the seconds surrounding Jessica's arrival at the M&M gas pump, there is no clear headlight pattern suggesting that she had left her home, then driven south on Carlisle to the dirt entry at M&M (near the puddles just before the intersection with US 51), and then proceeded to approach the outside pumps, and then swing hard-left into the inside pumps. (Note: In an earlier thread I had speculated on this as an obvious and routine approach from her house.)
Specifically, to see what I am describing you will need to watch very closely the opening 5 to 7 seconds of this clip from about 6:23:18 to 6:24:16.
[video=youtube;kxxyEHkOnhg]https://www.youtube.com/watch?v=kxxyEHkOnhg[/video]
Watching it will be very difficult because you are watching something happening in the distance, and are focusing your attention solely on headlight patterns of cars both arriving at M&M and at US 51's background activity. Meanwhile, the primary focus of the CCTV is really the arrival of the white station wagon which comes to a complete stop at 6:24:22. So you will need to watch the clip repeatedly and focus your attention on the background, not the foreground. (In order to perform repetitive viewing, stop the Youtube footage, advance the clip to the end, and then repeat. Using this technique, you will then not need to view the clip in its entirety. I recommend viewing the opening seconds a minimum of ten times before you draw a conclusion.)
Lastly, because the 5 - 7 seconds activity which I describe is seemingly unimportant the video's 6:23:18 to 6:24:16 is viewed in an overhead camera view before the cam operator has enlarged everything.
The reason I wish to bring these 5 - 7 seconds to your attention is because they imply to me that Jessica did not leave her home and drive directly to M&M.
In my mind, she may be approaching the gas pumps from the more northerly entrance off US 51.
Combine this possibility with the notion that she may have left home at 5 - 5:30 pm, and arrived at M&M at 6:24:39 pm, and we may have further reason to believe that Jessica's timeline begins at 5 pm.