His mother could have gotten them a week earlier? (Spoilers)

If I analyze that according to logic, it would mean that the mom purposefully didn't inform her son about the crutches because she wanted to continue things.

"If she had gotten them a week earlier the incestuous encounter the night before may never have happened because they would have had less physical interaction." - Not necessarily. One does not preclude the other. She could have had the crutches from the very beginning and the movie could have still gone the way it did. I went through what his mom went through (minus the incest) and I can tell you that even with crutches, I still would have needed much of the help that she did and I still would have needed the lotion rubbed on my foot the way she did.

Stop stealing! The government hates competition!

I think that he was in a daze...possibly denial...until Aunt Helen came to the door. My guess is that once they got out of bed at a slower pace, the guilt would have hit. Maybe not the panic, but the guilt.