The snow plow time is approximate. I'm not sure if the police ever checked GPS for the plow, but my guess is they did not. Because that would have been a normal investigative thing to do.
But I think it's safe to say whenever Lucky the Plow Guy first went by, John was still in the house, as Lucky has been emphatic he would have seen a body. The McCabes left Fairview at around 1:30 am and dropped off their two passengers locally, so Jen was home before 2:27. As far as we know, Jen didn't have further communication with anyone in the house, so her googling would have been in anticipation of the plan to dump him that had been discussed before she left Fairview.
To your point, did she have had some concerns that this plan might not work? That John might not die quickly, or be found too soon and somehow survive and tell? Was it her anxiety over this what caused her to stupidly google "hos long to die in the cold"?
After Matt McCabe left, the only other man in the house aside from BH was BH Jr., who suffers from severe anxiety (testimony). Colin and Higgins were already gone. I think this is why young and able-bodied Tristan Morris (now Caitlyn Albert's fiancé) was called to come to the house around 3 am, despite the fact that he'd gone home early in anticipation of working soon. Not only could he help BH move a heavy body out of the basement through the bulkhead, past the gate and to the front yard, but his vehicle could be used to block anyone from seeing what was going on from the road. This is the vehicle Lucky saw on his second pass. Even if Tristan had opted to not park in the driveway, there was zero reason for any vehicle to be parked in front of the area of the flag pole.
I also think he and Caitlyn Albert took Chloe home with them when they left to return to Easton.