Managing a group booking at a hotel and co-ordinating arrangements can be stressful for everyone, particularly if you are also managing a car pick-up service and international flights.
You can consider bringing forward your entire booking by one day, so that the guests in your group will have the opportunity to relax at the hotel, socialise with the group and make use of the hotel facilities.
Please remember to check the exact times with your chosen hotel, because this information is intended as a guide. The check-in time can vary with each hotel, but usually it is between 2:00 PM and 4:00 PM and the normal check-out time is between 10:00 AM and 12:00 PM.
If you have negotiated an attractive group rate, bringing everything forward by one day might not have a huge impact on the overall budget costs, but it might have a positive impact on the success of your group event, simply because it might be more enjoyable and less stressful for everyone.