Either zip ties or the spiral bands work fine. I've used both. I want to emphasize watching them to keep them from getting too tight, whichever ones you use. Yours should not grow a whole lot more but they will some. Depending on how tight they are initially, you may or may not need to replace them.
Cutler Supply has a chart on their site that gives which size spiral bands for which breeds. These sizes are for hens, not roosters. Rooster's legs are much bigger. I don't know how much larger you need to get the spiral bands for roosters, but I know they have to be bigger.
When choosing which colors to use, whether zip ties or bands, the darker colors show up a lot better on the legs that are lighter colored and the light colors show up better on those dark legs.