Distance training

I wondered how to go about training for this race. I got Penny Dean's book, Open Water Swimming, to help me plan. Apparently, I count backwards from the race day. About 10 to 14 days before the race, I do a straight continuous swim of the race distance ( 3 1/2 mi or 6,000 yd) 4 weeks before that, I do maybe 5500 yd, 4 weeks before that 5000, and so on. Each month during the week, I must try to increase yards. The workouts need to mix long aerobic sets with shorter speed sets. After the last long swim is the taper when one reduces yards and rests a lot (looking forward to that).