I have heard using a vacuum cleaner to suck the air out between the steel wall and the liner by passing the hose thru the skimmer opening.
You suck the air out then fill the pool with a couple inches of water then you can turn the vacuum off.
You then pull the liner sides up to remove the wrinkles. Then assemble the top of the pool.
I have also heard you leave the vacuum on and just pull the hose out as the water rises. This could take many hours when you are filling with a garden hose. I would assume the top rails must be on before you get much water in the pool.
I was reading some other posts that indicate the liner could stretch a lot (10"). Should I pull the liner tight when I secure it to the top rail when there is 6 " of water in it (I have an overlap style)?