I would set boundaries for him. I use to do that too as far as getting upset, yelling and screaming, but it didn't do any good. It just made my blood pressure go up.

I decided to get my girls up early. Especially the one that would always be late. You have to show your little one who is in control and be calm about it. I would try various methods. For example, tell him if you can't be ready then no TV for a week 2 weeks or anything he likes to do. Like, take toys away or games. Why does he refuse to put his coat on? You have to set guidelines and stick to it. This is what worked for me. My last child would really cut up in school and I would just take everything away from her, games, no TV etc... It worked after doing that a couple of times. I wasn't mean, I still showed her love, but there were things that I would not tolerate. Here is an article that you can read.
http://bit.ly/2jCnRYv