No, we surely don't know that. The way all this has played out, we don't know exactly when either Morgan or Hannah died, since there was such a delay between the time they disappeared and the time they were found, and with the condition their remains were in when they were found.
JM took off for Texas sometime after the afternoon of Sept 20 but before the afternoon of Sept 22, which I believe is when he called a family member from Louisiana.
He could have killed Hannah anytime between Sept 13 and Sept 21, imo. With skeletonized remains, can the ME tell exactly when death occurred?
To tell you the truth, I have been concerned about the time that elapsed between when Hannah disappeared and when the witness saw the buzzards on Sept 30. It seems too long for Hannah to have died on Sept 13 and the buzzards finally show up on Sept 30.
Don't know if there's any way to reconstruct the times in reverse, going backward in time from the Sept 30 date when we know the buzzards were VERY active. Sept 20/21 timeframe makes more sense to me as a time of death, but that's just a hunch on my part.
From the beginning, though, I've had it in my head that JM moved her on that weekend, the weekend of Sept 20/21.
ETA: You are right about the coyotes, I believe.