Keep any leaf that can be spared. You have to make an executive decision on what should be left. Say for instance: you have a fan leaf that is blocking light to a few young branches. Try to tuck the leaf under them so they get more light. If tucking the leaf is impossible, consider cutting it off completely. You should try to keep as many leaves as possible. When it comes to getting the light to the new branches though, most times the new branches will do more for the plant than a single leaf.
It is all about light penetration. I would say 85% of my leafs get tucked and spared. The other 15% that get in the way I cut off. Again, keep every leaf you can, but branch growth is important enough to lose a few leafs to make that possible. It is a decision you will quickly master and feel more comfortable making the more you must do it.
-Dude