Stop worrying about each attendee's availability! Just let each invitee enter their availabilities and the app will show the fitting time for everyone.
If you need a calendar to add your personal events: Google Calendar or similar. If you want to invite people to an event with a pre-defined schedule: E-Mail, Whatsapp, Google Calendar.
If your event doesn't have a schedule yet and you need to find it considering your invitees, then Reuplan is for you. Do you want to make a rehearsal and need your whole crew to attend? Here it is, you're welcome!