You dont have tons of room to grow them very big with that many plants, but i would keep them vegging for a while still. If you want the most yields and are not sure if they would be too big. Personally i think its better to grow bit too big plants and cut out the smaller branches or something to make them fit, than growing too little plants that doesent fill the whole space properly. But you dont want to grow them way too big and cutting out large par of the plants during flowering is a stress you want to avoid for sure.