I don't believe in ritual washing but I believe she might have changed if her clothing had been marked by (or she thought marked by) her menstrual cycle.
I've found a thing on his blog (at least it says it's his?):
http://jeremybamber.blogspot.co.uk/search/label/A%20life%20of%20Less%20LibertyIt says they had a beef herd in the shed next to the house: my brother-in-law has the same set-up except with dairy cattle, he's often up in the night if a calf is being born etc and certainly either he or farm hands seem to be out tending to them long before breakfast. So he might have been able to go to sleep easily, but if he knew a calf was due might have been out to it and come back in, or perhaps heard it in distress and got up to see if it needed assistance.
If he was in the kitchen, he might have heard the shots, telephonec for help, run up the stairs, met SC in the bedroom doorway and, without even seeing June, been shot at sufficiently (arm/throat etc) to need to retreat and then been chased back to the kitchen and stopped not from using the phone but from trying to get to the gun cupboard himself.
Have done some homework on family annihilators and discovered that one of their characteristics is the murder
is always planned.. So with that in mind, instead of the emphasis being on why JB asked when they would next be at the farm, perhaps it should be flipped and asked 'why did Sheila bring the children to the farm, a place she hated?' - perhaps because it had the family annihilators' weapon of choice: a gun.
Perhaps she was in the bedroom reading the bible to June, who was the prime character she thought needed saving from the devil?
I still can't think why, logically, she wasn't shot first in her sleep on her bed, as the one who had to be killed with one clean shot. But if she was complying it would have made more sense for that one shot to be in her mouth, not her neck as it's more deadly and more usual in suicides.