Jawwayne, It usually takes 10-14 days for the radiation effects to start, but everyone is different, and if you're having chemo, their effects start after a few days, some overnight, and with Chemoradiation the toxicities are greater. Radiation and chemo basically have some of the same side effects. Besides personal experiences, you can read all about radiation, and side effects at the below OCF link. You can make a post of your own, and get more responses. Good luck.

http://www.oralcancerfoundation.org/treatment/radiation.php

10/09 T1N2bM0 Tonsil
11/09 Taxo Cisp 5-FU, 6 Months Hosp
01/11 35 IMRT 70Gy 7 Wks
06/11 30 HBO
08/11 RND PNI
06/12 SND PNI LVI
08/12 RND Pec Flap IORT 12 Gy
10/12 25 IMRT 50Gy 6 Wks Taxo Erbitux
10/13 SND
10/13 TBO/Angiograph
10/13 RND Carotid Remove IORT 10Gy PNI
12/13 25 Protons 50Gy 6 Wks Carbo
11/14 All Teeth Extract 30 HBO
03/15 Sequestromy Buccal Flap ORN
09/16 Mandibulectomy Fib Flap Sternotomy
04/17 Regraft hypergranulation Donor Site
06/17 Heart Attack Stent
02/19 Finally Cancer Free Took 10 yrs