Top early, break apical dominance, increase transpiration for first 3 weeks to encourage stretching. Let the plant fill the space. Once apical dominance is broken the plant will grow like a candelabra rather than a evergreen tree. 🌲 For a better concept go check my latest diary. 4 autos in 4x4, good yield.
How much and what.ypu can do is greatly restricted by how much time you have, autos are not forgiving to hit or Scrogg. If you have a photoperiod then you can take as long as you wish within reason.