For me Frank, I sort of 'knew' from day 1, back in January.
I just woke up one morning with a numb bit on my lower lip--it hadn't gone away by the next day so I 'Googled' it. Being a 57 year old smoker and drinker , I just 'ticked all the boxes'
I went to the doc who said he had no idea, go see a dentist, went to dentist who was very young, but very thorough--full exam and X-Rays and immediate referral to Maxiolfacial surgeon.
The wonderful British Health Service meant it was April before I finally got to hospital, and then had to wait 3 weeks for 'urgent' MRI.
As it turns out, the wait probably didn't make any difference prognosis-wise, but oh boy, did my jaw hurt and look ugly for the 4 weeks before biopsy!

Brenda

Brenda in UK--Diagnosis 30/5/07--undifferentiated carcinoma in right jawbone and muscles. Stage 4
6/7/07--new diagnosis primary is in lung. Finished 4cycles of palliative carboplatin/gemcitabine
therapy September 07
Now dying to live!