On the first day of the tour you should be in Antalya at 15:30 at the latest at the airport to get to the bus station. The bus leaves from the bus station at 16:45. You can also go straight to Demre from any other city.
You should fly back no earlier than 18:30 on the last day of the tour or the next day, as there are few evening flights from Antalya.
You can edit the dates or times of the tour if you want to leave early in the morning or in the evening at the end of the itinerary.
Airline tickets can be taken without luggage and do without hand luggage, as you only need to take comfortable summer clothes with you :)