FIM is an acronym for a pruning technique. It is a way to reach into a plant in an effort to top it. Prune off the top bud. If you prune off or cut off the top bud, you should get two more.
FIM is when you reach in to the top bud and just snip off the top quarter to one half or so. Some say maybe 3/4 or so of the bud. I really was stretching I think to do it do these little guys. The pictures kind of show were I was going with the scissors. Open it up and get right down to the bud.
Looking at the plants with a magnifier it seems to be working.