Well I will tell you my experience. I had 10 hour surgery, and am almost to the end of 30 rounds of radiation, only 12 left, so i guess a little over half way through, but i like looking at it as almost done. Not everyone is the same, and I have had people tell me I will be able to get through just fine without a peg tube, and boy were they wrong. I wish i would have gotten the peg in before starting radiation.
Starting about a week ago, I wasn't able to eat or swallow anything, and I went 3 days with nothing coming into my system till they put a PICC line in and started giving me 2 bags of liquids everyday.
I am scheduled to have the Peg put in on monday the 28th, and let me tell you, that day cant come soon enough.
I have mouth sores on my inner lip, and on the entire left side of my tongue, because that is the only part of my real tongue i have left, also sores around the entire mucosa of my throat. They said they wouldn't show up until the 3rd or 4th week, but mine started to show up before the end of the first week.
2 weeks ago the thick nasty saliva started showing up and about a week ago I started vomiting about 5 times a day.

I am hoping none of this happens to you, but you may want to take precautions to be on the safe side. The minute you think you will need the peg, don't second guess yourself like i did, and just get it in. I regret not letting them put it in before my treatments, but i was nieve.

Hope you sail through this a lot better then i did. But neck and inner mouth radiation give you some pretty bad side effects.

Good luck and stay strong.