The manager of a peach orchard is trying to decide when to arrange for picking the peaches. If they are picked now, the average yield per tree will be 100lb, which can be sold at $0.80 per pound. Past experience shows that the yield per tree will increase about 8lb per week, while the price will decrease by about $0.05 per pound per week. Using calculus, determine when the peaches should be picked to yield the absolute maximum revenue.