Of course it is easier to change things before D. Basically, before anything is put to paper and placed before the court, make sure it is what is best for you and your son. Based on how he has been acting I would wait until you have to sign before doing so. But also keep in mind that long-term you want your son to have a healthy relationship w/ his father, so don't be punitive now in regards to that. Make sure the opportunity is there for the healthy relationship in terms of the time allotted to him. How he handles himself and how he takes advantage of that time is up to him. If he does his job as a father right, then things won't be so tuff on you in terms of how you have to handle your son. In a perfect world both D'd parents would make their children the top priority, but that just isn't the case many times. You expect him to conduct himself in a similar fashion as you conduct yourself, and he just isn't willing to do that right now. That is really all it boils down to...
I agreed to stuff in my D that has come back to bite me a bit, but nothing compares to how I've had to take extra special care in how I conduct myself and my relationship with my four kids. Their Mom didn't handle anything with discretion or sympathy for her kids, basically put them through a combine. While I did hit a point this past summer where I thought I might have to GO BACK to court in order to get them with me more, it passed. I figure there will be ebbs and flows in this as time moves on, but in the end I'm sure it will settle down. She told me once that we had different parenting styles (of course we didn't pre-sep & divorce) and that I would have to deal with her elected style of parenting. Bad as I hate to admit it, she is correct. As long as she isn't abusing them then I have to let her live her own life as a parent. In the end, how she elects to live that life and fulfill that role will dictate her kids view HER. How I live my life and fulfill my role as Dad will be how they view ME. I can't control her actions or what my kids think of her. I think the same holds true for you.