...I am so sorry you are facing Efudex treatment. You bring up some really great questions, and your concerns are more than valid. Don't hesitate to come to this community when you need us...we are here for you, and we understand.
I am an elementary teacher, so I more than get your concerns. I treated a large portion of my face a few years ago, and waited until the summer to do it. While it is more difficult to treat in the heat of summer, I didn't have to worry about dealing with school while going through the side effects of burning and itching while sporting a bright red rash. It's impossible to say that you will have the most difficult of side effects, but there is a possiblity you will have some discomfort and irritated skin. For me, the first two weeks were tolerable, but the last two weeks of the four were terribly uncomfortable. I also felt it was difficult for others to look at me. I wouldn't have tried it during the school year, to be quiet honest.
As far as taking off work goes, the only area I have treated during the school year that required any time off work was my chest. The healing process is quite difficult during the first couple of days post treatment, and I took off a few days until the worst part was behind me. The chest is easier to hide, and I was able to work up until the healing phase began.
I don't want to begin to tell you what you should do--I can tell you that I imagine your job to be challenging enough, and the possiblity of extreme discomfort would make that job even more difficult. I would advise you to speak with your doctor about your concerns and ask if it would be possible to spot treat the areas of concern one at time over month or so. Keep in mind, the larger the area, the more difficult the treatment.
We all seem to react differently and at different rates. In addition, we heal at different rates. In my experience, it takes several weeks for redness to subside. Once any scabs work their way off, healing can move very quickly. I do have some flareups of redness over a few months following treatment when I get hot. It's only a guess, but I would say that you would be feeling normal by April.
I am including a few articles that may help answer any questions you have about side effects, redness, and healing as well as one on spot treating.
https://skincancer.net/life-with-skin-cancer/tips-for-efudex-users
https://skincancer.net/life-with-skin-cancer/efudex-redness
https://skincancer.net/life-with-skin-cancer/efudex-side-effects-tips
https://skincancer.net/life-with-skin-cancer/spot-treatments-efudex
Here is an article on how I handle telling my students and their parents about any treatments I do during the school year.
https://skincancer.net/life-with-skin-cancer/efudex-work
I am wishing you all the best as you move forward. It can be very overwhelming--just know you are never alone in this! Reach out to us any time!
April, SkinCancer.net, Moderator