Hello, this is Alice from Yeha tour.
First of all, thank you for your interest in our tour.

Our Tour Operates...
▶ Bus Boarding Time : 08:40am ∼ 09:00am (Departs at 09:00 am)
▶ Bus Boarding Place : ＂B2-Parking lot＂ of ＂Jeju airport＂
▶ The guide will be holding a picket with our logo [Yeha]
▶ Ends around 6:00-6:30pm.

If it´s the flight is 8 am arrival, it seems that you can participate the bus tour without any major problems.
It´s hard to tell how long it takes to find your luggage, but is usually takes about 15 to 20 minutes on average.

FYI, I will also attach additionally information as below.

Thank you.
:)
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Yeha Bus Tour
▶ Different courses for each day of the week.
▶ Professional Qualified ＆ Skilled Tour guides
▶ Lunch, entrance fees are included
▶ You will have around 40∼60 minutes of free time at each destination.
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Possible options by separate request...
▶ Vegetarian menu
▶ Bringing Luggage
▶ Returning separately from the last destination is possible