Second question from a new AGP owner

Due to overwhelming pressure from Household 6 (My wife), I filled the pool even though there is about a 4" difference between the high and low side. Well since I'm super duper smart, I have decided to begin leveling a different part of the yard while I keep the pool up as is. There isn't much bulging or any signs of excess pressure on the lower side (Apparently Intex takes morons into account when building their pools, thankfully).

Before I begin this three-hour tour, I figured I should get some advice I will actually accept. I have a 15' x 48" round pool, and have marked out an area 18 feet in diameter. Thanks to another member on here, I now know I need to level by removing soil from the high side rather than adding soil or sand to the low side. What I'm not sure of is where to level from. Do I find the lowest point and level the area from that or do I use a board with level attached to the center stake and check for level from the center out, or do I combine the two and level from the low side and verify from the center out?

This may all seem very elementary to some, but all I'm really useful for is shooting things, smashing bugs, and turning wrenches. Landscaping is an all new skillset for me. Any assistance is appreciated.