Sweet a math problem
lets see...315lbs - 235lbs = 80lbs
Assume 5 lbs per recovery cycle (I have no idea what your recovery cycle is.. novice, advanced novice, or intermediate)
80lbs/5 lbs per recovery cycle = 16 recovery cycles.
If you are on the novice progression that will be 16 workouts..approximately a little more than 5 weeks.