There's great advice here. I get mine banded the first day, after they nurse and lay down. Seems like no stress at all for them. I have been out of pocket/out of town and my bro-in-law took care of some for me.
Since I don't live down there, I bought a big pistol carrying box. It will hold the bander, bands, ear tag applicator, ear tags, syringes, a nursing bottle and powder cholesterol etc. There is more real estate in that box than I thought. Anyway, those little boxes are waterproof, dustproof etc. You can bet some day you are going to be working in a muddy/raining environment. It is also nice to hand off the box to someone who if filling in for you. There is room in there for a good sharp razor/side cutters/end nips/zip lock bags etc. The foam top shelf holds the important stuff pretty tight and the box is pretty deep. It helps me keep up with EVERYTHING.
The only thing I didn't see in this thread of replies was the age of the bands. Bands are cheap. I toss out old ones. I buy new ones each year. I also look closely at the packages I buy to ensure they are fresh.