I had similar surgery plus a few other things done on top of this 6.5 weeks ago. Was in back slab plaster for 10 days (NWB), then fibreglass plaster for 2wks (NWB) and then ankle brace and WBAT on crutches to come off these over 1 to 2 wks. It was very painful to put weight on my foot again after 3.5 weeks NWB and the surgery.
It took me a week to get rid of the crutches totally (used both for 2 days, then 1 for 5 days). Still really painful to walk on and stiff etc, but I did start physiotherapy 3 days after coming out of plaster and have been going twice per week since then.
Each day there is a little improvement (a couple of times I felt like I have gone backwards - like today) - but I am focussing on healing and improvement.
Just take each day as it comes - the pain will improve over time.
It really fascinates me how each OS has a different protocol after similar surgeries.
Sorry, I can't comment on the aircast splint, other than to say that I have to wear my brace all day, every day for 6 to 8 weeks, and then only for long walks, treadmill at gym etc for another 3 mths after this. I was told I could take it off at night and if I am going to be sitting down for a while so I can do ROM exercises.
Hope that helps - don't forget, you are now putting full weight on the ankle and it's going to let you know for a little while.
Hope your pain improves