Working Week Completion
Python 3, 132

from datetime import*
t=datetime.now().timetuple()
m=max(0,t[3]*2+t[4]/30-18)
print(20*min(5,(t[6]+min(15,m-min(8,max(7,m))+7)/15)))


The resolution is one minute, or 2/45 of a percent. That's more than enough IMO.