Pruning Seedlings to Slow Growth and Stop Shading

Q.  There is a passage on the CD that states… to slow plants down for a week or so, pinch off the two first “true” leaves.  Do I leave only the seed leaves?  What about the growing tip?  I suppose pinch refers to using pruners, also, or does actual “pinching” have some significant benefit over pruning shears?  And I suppose this “pinch” would be closer to the leaf itself, than the main stem, to keep from wounding the main stem?
 
A.  You do nothing until the plant has several sets of leaves.  What we are trying to accomplish is that after the plant get so big it is crowding other plants, you can accomplish two things by taking off the oldest leaves (still leaving the newer leaves).  You shock the plant slightly by removing the leaves, which slows its growth for a few days, and you stop those large leaves from over-lapping and shading the adjacent plants.  You will generally use your finger and thumb nails to pinch off the leaf, and you will do so next to the stem.