He's 6 inches already, so I would say not to great. But don't you have this guy is a community? Try putting him solo and extra TLC and see if he pops any bigger.
The more aggressive and pissed off that they are the better it is for them. Their color pops alot more when they are mad and feels dominant. Kok size is based on genetics and how big of a pig he is. The more he eats generally the bigger his kok is. Its pretty much just a storage of fat. Not feeding him for 3 days probably really hurt his size.