Gastrocnemius tear - ski boot cast query

I have a partial thickness tear in my gastrocnemius muscle. It happened 4 days ago - had a us scan to confirm tear. Could not weight bear initially but had a back slab plaster applied and was given crutches and could partialy weight bear on tip toe. Went to clinic yesterday and ortho doctor advised review in four weeks - put in a ski boot cast.

The boot has dials on either side where you can fix into dorsi or plantar flexion. My problem is that the doctor I saw did not seem to know what the best position was and just left it with FROM and I am struggling to walk or partially weight bear in it as I can't weight bear on my heel. Spoke to a physio I know today and she advised that I keep the muscle short so toes pointed for the four weeks and she says this will help with scar tissue? I am confused and dont know what to do for best with the cast - any advice??:(