I got conjunctivitis (not severe, just beginning), how long would it be until the redness goes away on trimethoprim polymyxin B ophthalmic eye drops.?

CONJUNCTIVITIS . Conjunctivitis is very contagious with your symptoms it sounds more bacterial than allergic . Redness tends to resolve in 1-3dys. You can add in ZYRTEC (cetirizine) &PATANOL DROPS to cover any allergic component.