Apart from typos KenYou can wire at any time, gut with a deciduos tree, the growth will be so fast the wire will cut in before the new wood sets into place, and you will probably wave to take it off and rewire it. Do not let the wire mark the bark on a male as it will scar for ever and look ugly

1. I believe that branches set into place when new wood = strength of old wood. For any given branch you just need a certain amount of new wood to hold the old wood in place. In summer that happens quicker than in winter. If the wires cut in during summer it is just that you do not take the wire off quick enough. Young branches will be set in place in a few weeks, older wood take longer but it does not matter whether winter or summer, just happens much faster in summer.
2. even scars on maples are not 'for ever' - just a long time. They do grow out, eventually.