Second is to restrict your internet use to specific times or to just say an hour every night from 9-10pm. Lets say start out by saying internet only from 0-15 minutes on the hour (initially). The idea is to get you used to not reflexively use the internet to prevent boredom or distraction.
How you accomplish that, say by killing your internal dns server to not respond or even firewall off your network from reaching the internet is up to you. But the key is to make it so you change your habit of when using the internet is ok.
Oh also, leave the phone at your desk, only pick it up when you need to look at it or if it rings etc...
Another good tip, reward yourself for each milestone, you want to encourage yourself to do the right thing. Don't use negative reinforcement unless you really know how to make that work. Its easier to do stuff like: if I don't go online at all today, I'll eat a container of ice cream (bad example if you do this every day but you get the gist) as a reward.
I also turn off the ability of most apps to display notifications. That helps.