Usually a few days or a few weeks is enough ... just old enough
so that it doesn't fall off. A bit of hair also helps.
The proper way to wear a yarmulke is to wear it on the Sabbath, Shabbat, or when in Shul. One should wear a yarmulke whenever everyone else is wearing one.
A yarmulke, also known as a kippah, is a small, round skullcap worn by Jewish men as a sign of reverence and humility before God. It is often worn during religious services and at other times to show one's connection to their faith.
Yes
Orthodox Jewish men wear the Yarmulke all the time. Other Jews (male and female) decide for themselves whether or not to wear it.
No. You don't have to be orthodox to wear a yarmulke. In fact, you don't have to be Jewish. Some modern liberal Jewish congregations have pronounced the yarmulke optional during services or have dropped it completely, but it is still primarily a matter of individual choice. There are even some Jews who are quite secular, do not regularly pray or attend synagogue services, but who wear the yarmulke in general daily life.
Yarmulke
Yarmulke and Yashmak
Orthodox Jewish men wear a yarmulke (a skullcap). It begins with the letter Y.
Jewish teachers (rabbis) typically wear a kippah or yarmulke on their head.
A kippah, or Yarmulke, or a hat or streimel.
Yarmulke (Yiddish) or kippa (Hebrew).
A kippah, or yarmulke. http://en.wikipedia.org/wiki/Kippah