i dont wash my hair before applying at night, in the morning i shower then wait a few hours till midday to apply it. it means i have to put it on in work which is not ideal but i find i dont have the time in the morning to apply it, and also i have just showered and made my hair look ok in the morning, putting minoxidil on it then straight away gives it that slightly greasy look.
thats just me, its probably not the optimum way