Lay the top on a flat and soft surface with the pockets facing upward.
Fit the first leg into the pockets without the drill holes going through the top.
Fit the next leg into its corresponding pockets.
Make sure all pieces sits tight and flush with minimal to no gaps. Flip the stool over so it stands on the floor.
Drive in the screws using a non-electric flat-head screwdriver. Stop when the head is flush with the surface; avoid over-tightening.