As stated already, I definitely agree that it's more likely that any foul play at the Ristevski residence happened at night.
That said, whilst human witnesses may be less likely and less accurate in the dark, CCTV cameras near the Ristevski home have no such disadvantage at night. Most see quite well at night, and those that don't will still have faithfully recorded any comings or goings of any relevant vehicles. So the police should be well aware of any trips taken using any relevant vehicles that started from the Ristevski home.
Whilst I readily accept the possibility that Karen met her end on the 28th of June, I think it's quite likely the disposal of her body happened the next day. That ties in nicely with the drive Borce took in Karen's car, that he just happened to forget until confronted with phone ping data. Once confronted, he explained it away by saying it was to address a fuel gauge problem, a claim that has been thoroughly debunked. Early reports of the fuel gauge claim said Borce claimed to be taking the car to a mechanic to get it looked at, I wonder if he can prove that he was booked in with a mechanic that day?
What interests and confuses me is that if Borce's phone pinged on the Calder at night on the 29th & it was being confronted with the phone ping evidence that triggered his memory of driving Karen's car between about 10am & 12:30pm, then perhaps his phone was detected out that way twice? Once in Karen's car during the morning of the 29th & again at night the same day, perhaps on another vehicle? There is also the 2 hour period that day where his phone was switched off, but I've seen no indication of what time that happened.
Another pointer in my mind towards the disposal operation happening on the 29th, as opposed to the night before is Karen's phone pinging out towards where she was found on the 29th.