You were already told that yes, 15 extra days of veg can make a significant difference.
You never mentioned what lamps you have though. If you don't have enough light to cover all the plants properly as well as get good penetration into the lower portions of the plants, it won't mean a lick of difference, and you could end up hurting your yield instead of helping it.
If you've got adequate light, and those are five gallon pails, I'd veg for another 30 days or longer before flipping. You've got the floor space for it. If you've got the lights and adequate temperature and humidity control along with airflow, I'd let those plants fill out a lot more than what they are now.