Ok, once you've gone as far as the clothes pegs, stop and continue with thses instructions in order to get a wrinkle free install (well...best chance anyways).

Before you unroll though, just make sure your base is still good, pick any stones or foreign objects out etc.

Once clothes pegged, try to center your liner on the floor as best as possible - this means left right front back adjustments as best as you can, trying to line up the weld seam where floor meets wall of the liner, getting it spaced evenly all around the inside of the pool.
Next step is to just pull the liner so it's elevated off the floor around the edges a slight little bit, maybe tug it over the wall another 1" all around, start to fill from the center a,d if you see wrinkles on the floor try to work them towards the edges. You won't be moving much liner under 6" of water - 1-2" is preferred.
once you're close to the edges with the water, you will need to give the liner a little slack - remove the clothespins and the liner should slip in as needed as the water creeps towards the wall.
If you hung the liner properly, it should not have any angled lines in it when looking at the wall, if it does, stop filling, and readjust the top of the liner from side to side to remove these angled lines, continue filling, once you're filled to just under the return, mount your skimmer and return jet - cut the return jet hole from outside the pool, on most pools you can mount the skimmer and cut the opening out after it is mounted - this is Dennis' preferred method I believe.