The use of staggered nutrients is good. I generally suggest adding the nutrients at a given point in the fermentation based on gravity, not based on number of days because I have had complete fermentation is as little as 48 hours, and giving nutrients after a fermentation is finished is just feeding potential spoilage organisms.
I'd add the first nutrients as soon as there is some visible sign of fermentation after pitching. This is the end of what is know as the lag phase and it may be at 8 hours, or it could be as little as 2 hours or as much as 36-48 hours depending on the yeast, temperature, and preparation.
I'd add the second batch at the 1/3 fermentation point (when the gravity has dropped 1/3 of the expected amount). The last nutrients I would add at the 1/2 fermentation point. Beyond that time, add DAP does not help as the yeast cannot assimilate it late in fermentation.
As for the amount of nutrients, what they indicate for the 5-gallon batch should work if you use the 71B yeast. If you use the D47, I'd use 50% more as it tends to need more than 71B.
One last small item. Per BJCP guidelines, the term "Show Mead" refers to a mead that is made using only honey, water and yeast, with no nutrients added. If you add nutrients, the correct term is a "traditional mead." Recipes that are called show meads which use nutrients are a bit out of date.
Medsen