YMG, it seems to me that you are being too hard on yourself. I also partied a little in my second week here but didn't do anything after that, I can tell you that beating yourself up doesn't help.
Also, don't try to do everything at once, I have made this mistake so many times. I say to myself, "yeah! today I am going to work for 8 hours!" At the end of the day I work for only one hour and nothing gets done, i have been more productive on days when I decide to work for only 4-5 hrs. The most important thing is consistency, if you burn yourself out by either working too much or thinking/worrying about work then nothing gets done.
Also, don't try to do everything at once, I have made this mistake so many times. I say to myself, "yeah! today I am going to work for 8 hours!" At the end of the day I work for only one hour and nothing gets done, i have been more productive on days when I decide to work for only 4-5 hrs. The most important thing is consistency, if you burn yourself out by either working too much or thinking/worrying about work then nothing gets done.