One thing I've seen in instructions, especially videos is, they will mention to start on the straightest wall. That seems logical. It doesn't really matter if the wall is wavy or crooked. It's a very rare day when you will start your first row of boards without cutting them.
Snap a chalk line the distance out from the wall, that the second row will meet the first row. Next, put the first row of boards together, but line them up along the chalk line in the position of the second row. Now, you want to line your row of planks up exactly on the chalk line. All of the and joints should be locked up perfectly just as they would be when the flooring is installed. Now starting at the far end of the room, take a 10-in scrap of one of your planks and position it tight against the wall and overlapping the row of planks that you have lined up on the floor.
This 10-in section of plank will be your measuring tool. With the plank tight against the wall, and overlapping the first row, draw a line on your plank, using that 10-in piece as your guide. Draw a 10-inch line, then carefully slide your scrap 10 in down and draw another line, and another. Continue all the way down to the other end of the room. Be very careful when doing this so you don't bump your row of planks. Out of alignment. A very fine pointed sharpie can work to draw the line.
I haven't paid much attention to what is printed in instructions when doing this, so I don't know if the instructions that you have mentioned this.
Now remove one plank at a time and cut as carefully as you can down the length of the plank and put it back in its final position. Be sure to put a spacer between the plank and wall. Now do the same to the second plank, then the rest, each time locking together the end joint together before cutting the next plank. Use that 10 inch scrap as an alignment tool to be sure the and joints are perfectly aligned.
When cutting the planks, either cut your marker line all the way off or leave it all the way on. Be consistent The more accurate you can make this cut the better.
All that you're doing in this process is creating a perfectly parallel line from the wall onto your first row planks using a scrap piece of material as your guide.
I will even go as far as laying a strip of masking tape along the row of planks, and then instead of a sharpie, use a ballpoint pen which creates a very fine line to make your cut more accurate than a sharpie.
