and thank you so much for your question tonight. I hope I can be of some help and assistance.
There is not a simple yes or no answer to your question. This is because there are different "grades" of mast cell tumors, ranging from quite benign to very aggressive and malignant. If you knew for a fact this was an aggressive form of mast cell tumor, you would want to get it off as quickly as possible. The challenge is, we really don't know how aggressive it is until after it is removed. At that time, these tumors are usually sent to a pathologist for review, to confirm that they are indeed mast cell tumors, and to grade them in terms of how aggressive they are.
This article explains the forms of mast cell tumors well:
About 50% of mast cell tumors are grade I, or more benign. These may enlarge locally but do not spread elsewhere in the body. If your dog's mast cell tumor has been there a long time and has not changed much, it is likely grade I. But again, we don't know for sure until after it is removed. Waiting a few weeks to remove a grade I tumor should not be a problem. Your vet may feel this is likely a low grade mast cell tumor, which may be why the surgery is not scheduled right away.
Hopefully now you understand why I can't give a definitive answer to your question, as it would depend on each individual case. If you are not comfortable waiting 2 weeks, I think you should ask your vet to please get you in sooner. In general, the sooner the better.
I hope this helps, and let me know if you have additional questions.
Thank you, XXXXX