You can manage your Calendar settings from Settings >> Registration >> Calendar Settings >> click 'Edit'.
These settings allow you to control:
Show attendee counts? - Show number of attendees for classes and courses to customers?
Calendar starting day of week - determines which day of the week your calendar starts on. Choices are to use user's preference, Sunday or Monday.
Days for weekly limits - for memberships with weekly limits, we'll calculate usage using your choice - Sunday through Saturday, or Monday through Sunday - as the week.
Dates for membership limits - this setting allows you to choose whether membership usage limits should be aligned with billing dates or calendar months and years. Applicable to monthly and yearly membership limits