JD was back home from dropping the children at school around 8:15 - 8:30 am according to a friend who was the last person who spoke with her on the phone around that time, as LE reported to MSM. There has been no information on whether FD even knew the housekeeper's schedule -- they had been estranged for 2 years, and had separate households, and the only time he spent with the children was during supervised visits, and he wasn't allowed to speak with them on the phone unless it was on speakerphone, per Court Orders in their divorce proceedings. The point being, there isn't an obvious way for FD to know the housekeeper's schedule, since he wouldn't be allowed to have casual conversations with anyone in JD's household about her employees and their schedules (nanny, housekeeper, landscaper).
So it would be a stretch IMO, for FD to have known or cared that he 'only had until 12;00 pm' when a housekeeper was coming. Either way, that's a 3.5 hour window. IMO it all was supposed to go very quickly without a struggle, and even with the struggle and the blood that had to be cleaned up, it wouldn't take very long to do that in the heat of the moment (maybe 1/2 hour), then to move her body and her vehicle 3 miles to Waveny Park, and / or then jog to a nearby location where the vehicle he was using was parked (maybe 1/2 to 1 hour), all with time to spare and make the 70 mile drive back to Farmington where FD's cell phone pinged at 1;30 pm, according to LE. All JMO on FD having ample time to do what he did.