The basics we followed with summer gelding:
~Swat or similar thick fly repellant-twice a day if needed ( I say use the thick stuff so you can control what tissue it is touching. Nothing like spraying fly spray and getting kicked cause it burns)
~Thermometer-check temp per vet instructions (We did ours once every 24 hours for the first 5 days unless the situation called for more often)
~Smallish paddock,corral,round pen, for the first 24 hours or so. Somewhere you can keep a close eye on him and make sure he isn't bleeding. Coming out of the anesthetic he'll be wobbly and unsteady for a bit. This also comes in handy if you have to MAKE him move and exercise.
~Access to water hose for cold hosing.
~Fly mask, nothing worse than flies at both ends (We tried fly sheets and it just doesn't seem to work well with the drainage, they get icky and attract more flies I think)
~LOTS of fresh cool water handy. My last gelding blew through a lot of water in the first 72 hours.
~Slow feeding hay bags if not on grass. He'll keep moving if you can place them throughout his area. I usually put 2-3 (depending on how many I had on hand) and make them walk for their dinner. I broke their feed up into smaller portions and put it in 3 other spots so they had to walk for it too. I have been known to cheat and dribble alfalfa cubes in 10 different spots to help keep them moving on the hard cases.
~ We usually kept our geldings separated from the mares for about 4-6 weeks after gelding. I am sure your vet will let you know what he prefers.
Trust your vet. They know the problems in fly season and hopefully will be helpful in avoiding infection after the gelding. Good luck to you and him
Excuse me if I left something out, or you already know this info. I'm not a vet nor do I play one online