Why is it so that I have 8 hours to work, but find myself to only be productive in the last 2 hours... I find it difficult to work in the mornings, to much chaos up in my head.

I'll loose the job if I continue so, any tips?

Must people are only productive between three and four hours a day.

Had very similar problems in the past. In my case it was because of lack of sleep, which became better over the years. What does help is to at least do little bits of productive work, peppered throughout the first 6 hours, because all those little bits add up, and you will notice a difference in your daily output. It will also train you a little to become better at focusing your mind.

Had a similar experience. In my case I lacked focus and wasn't able to accomplish much throughout the day. Music helped. But not just any music. Try game music or movies' original sound tracks. These are specially created to have the player/viewer concentrate on the game/plot of the movie. Avoid anything with a lot of lyrics in it. Nowadays I have my headphones on with Dark Knight OST playing. My productivity has improved quite a bit.