To answer your question,yes,many bulldogs dogs do "turn on" about two years.In case you aren't familiar with the tern "turn on" Its basically when the dog starts to act like most bulldogs and tries to kill any other dog that comes near it.And it can happen slowly or quite suddenly.All bulldogs American Bullies included have a very strong potential to be dog aggressive,its in their blood,what they were bred to do.You can train a lab not to run after and retrieve anything it feels like,but you cant train the urge they have to do it out of them,and who doesn't give into urges every now and then?I understand you wanting people to know that "pit bulls" aren't bad dogs,but taking them to the dog park is not a good way to educate people,because if your dog gets into a fight,it doesnt matter if the other dog started it.The bulldog will ALWAYS be blamed! And while your dog may think you can control your dog from fighting,you need to always remember:A Bulldog wont always start a fight ,but they will damn well finish it! What might just be a scuffle between two other types of dogs can quickly escalate into a situation where only one dog comes out alive,when a bulldog is involved.It's what they have been bred to do ,fight till the end.You can control this to a point,but you will not ever train it out of them.So for all those reasons,dog parks are not a good idea.There are other ways to promote the breed and show them in a positive light.I seems like you have good intentions,but seriously please keep your dog far away from dog parks before something awful happens.Everyone here knows its BS and unfair,but,I cant say it enough.THE "PIT BULL" WILL ALWAYS BE BLAMED FOR ANYTHING BAD THAT HAPPENS!You will be doing yourself,your dog and the whole breed a favor if you just dont take the chance.