Thinking of getting lip filler. However, I am due to receive a date for tonsillectomy. Should I wait until after my surgery?

I think it is best that you wait until after the surgery for the fillers to the lips. You don't want to compromise the results of the filler by the manipulation of the mouth and lips during surgery. Get a consultation from a Board Certified Dermatologist about two weeks after the tonsillectomy when you can expect swelling of the mouth to be minimal. 

I would definitely wait until after surgery  to have  your lips injected .  You should ask the physician who is removing your tonsils how long he or she recommends you should wait .  You don't want to have any inflammation in your mouth when you have your lips injected .

I would definitely wait until after surgery.  Any oral surgery, including dental work, can stretch the mouth and decrease the longevity of fillers in the lips and around the mouth.