Pretty sure your yield will be mostly dependent on the size of your plant and number of colas, along with proper care.
You should top it after 4/5 or so nodes and try and focus on spreading your canopy out evenly taking up as much of the light area as possible. Look up manifolding and LST techniques. Manifolding might be drastic, but something like that can help you to get a good flat canopy. Try to train it grow outwards rather than upwards. You can also just bend it and allow the branches to grow upwards while the main stem is growing more horizontally. It will double in height once you flip to 12/12 so that will be the main determiner for you when deciding to flip. 30cm might be the right height. I don’t think you have the space to let any other factors decide when you flip.
I’m also not a very experienced grower and could be wrong about everything.