My wife starts with headaches at 8000 ft.
Dr give her Diamox 250 mg and our plan was similar to yours.
First night at Horseshow Meadows, walking to Cottonwood Lakes second night, another night at HSM. Next one Outpost Camp, another in Trail Camp and last one at Outpost again.
She cut the pills in half (125 mg each one) and took one each morning, and one at around 7 pm every day starting the day we arrived to HSM.
She had headaches every single night, except the last one when we came back from the summit.
She had no problems while hiking during the day, even at the summit.
We still don't know if Diamox worked, acclimatation worked or both together, but the fact is that she spent 40 minutes at the summit and is now very happy with the trip.
