Real Time > Settings (/admin/realtime/settings) has a Save button at the top and three sections:

1. Order Buffer Time — one field, Order Buffer Time (minutes).
2. Realtime Fulfilment Days — seven toggles (Sunday to Saturday). Hovering shows "Can this realtime start on Mon?" etc.
3. Times — for every enabled day a block with the weekday name, the time windows already saved (each with Start and End time pickers and a red Delete button) and an Add New button.

After saving you are returned to the page with a green Done! message; validation problems show in a red alert above the form.