the more systematic you are at filling the space, the better the yield will be. with many plants in a small space, this is less important but can still help. you should need a ton of training as these plants will quickly fill in the gaps just growing normally. you'll still more easily and more quiclkly get X vertical colas per sq ft in a systematic manner.
the axillary growth (axillary buds -> branches) will eventually be more substantial, though some strains do not branch as much as others. What you see now isn't representative of a more mature plant, more times than not.
remember, you only have to fill about 1/2 the space by the time you flip to flower... if autoflower, it's a crapshoot in that regard as they all have different time frames for development. when you see preflowers, figure flowering started 7days prior or more.