The place and time has to be decided by the needs of those attending and can vary from time to time. Places can vary from someone's home - to a space that feels comfortable and has good energies. Consistency seems to work best here as it builds energy. The length of the class may vary depending on the day of the week. Taking a break during the class - and serving refreshments is optional.
Many people serve tea and cookies.
Class size can be as small as two people or as as many show up for the day. Most peope prefer an evening class but daytime classes are just as powerful. Some people focus on celestial timing such as full moon energies. This is up to the group. The selling of products is also up to the person holding the class.