Hi,
Unless you have been specifically told by your GP to stagger the dosage, it's really best to take the whole lot in one go (and from the sound of the bottle instructions, that's what you're meant to be doing). Bear in mind that your body would naturally produce corticosteroids in the morning, so this is the best time for you to take the Pred - preferably with breakfast. As already mentioned, you're less likely to have trouble with insomnia if you take the dose early in the day.
Good luck,