Well earlier in veg you could have trained (e.g. LST, supercropping, topping...) your plant to widen up the canopy. With the natural Christmas tree shape you'll have to just add support for when the buds make it top heavy, depending on how fatty you make the colas.
Do you have more fans on them? Getting good air on them can strengthen up the stems. Plus you'll want really good airflow on the buds to prevent rot.