There could be various takes on flexi timings, and you can choose whichever is suitable for your organization:
1. You can allow people to come and go at their will as long as they complete the required hours per day, for example, 8.30 hours in your case.
2. You can permit people to come early, complete the required hours, and then leave early, for instance, from 9 am to 5.30 pm, or vice versa for late arrivals and departures.
3. You can request employees to arrive and leave at their preferred times, but they must be available in the office during core hours, for example, from 12 noon to 5 pm, and complete the required hours.
4. You can let employees leave early or arrive late on specific days as needed, and they can make up the remaining hours on other days.
There are more options available; choose wisely and establish a proper procedure and guidelines before making it official. If necessary, you can conduct a trial run for a few days.
Thanks & Regards,
Pranali G