Hi @kranate
Thanks for reaching out.
To confirm, are you referring to Export Appointments option allows synchronization of all of the upcoming events with the Google Calendar of the staff? If you add it to your Google Calendar for the first time, then the events will show immediately.
However, if there are updates from the external calendar, the timing of when those changes will appear in your Google Calendar depends on how frequently Google Calendars synchronize events from external calendars. According to my research, it may take up to 24 hours for any changes to be reflected in your calendar.
I hope this helps. Let me know if you have further questions or concerns.