What kind of recovery time for rare large lipoma removal?

From what you described, I would perform your surgery as an out-patient. It's possible you would benefit from a drain, or tiny tube to drain liquid from the wound site, which would be removed approximately 1 to 7 days later. Depending on how physical your job as a teacher is, I would think you could return to work in 5 days. 

*Opinions stated here are only opinions. They are not based on a clinical exam which is recommended.*

Thank you for sharing your excellent question and best wishes on your upcoming procedure.  You can likely return to work within a week’s time, but ultimately it will take 6+ weeks before much of your discomfort and swelling has resolved.  Hope this helps.