I had 5 or 6 weeks of Erbitux - it was rough for me because it caused quite a severe skin reaction as the weeks progressed. I felt that the rash got worse a day or 2 after each infusion, peaked at about day 3-4-5 and then diminished ever so slightly before the next infusion. Overall though, it did get progressively worse. I was looking at my CA journal a few weeks ago and there were days where all I wrote was "rash, rash, RASH!!!" So it's no fun at all but manageable - my oncology nurse said even though it looks like acne don't treat it like acne by using alcohol products. I used aquaphor and aloe vesta like crazy. I was about to ask for silvadene at the end because it was getting pretty painful but they decided to skip the last infusion.
Just a note - it seems obvious now but it wasn't then- I'll blame the pain meds - but I was very good about NOT using the pastes and creams before radiation because it interferes with the radiation BUT I was not smart enough to realize that the aquaphor I had plastered on my chin was actually in the radiation field too and so I ended up looking like Jay Leno for a while! So be careful about that - CLEAN skin makes a big difference!

My skin took about 2-3 weeks to heal after the infusions stopped - the MD assured me that there would be no scars as a result of the rash but he was wrong - I do have some scarring on my chin but as I mentioned above I may have contributed to that inadvertently!
Good luck - I didn't call it "Erbisucks" for nothing - it sucked but if it worked then it was worth it!!!!!
Take care Mike!