Hi Jan
Your tour manager or airport rep will be at check-in from around the time it opens, which is likely to be about two hours before departure.
Personally, I often get to airports quite early in case I am held up on the way. If I were you I would have a look around the shops or find somewhere to have a meal or a coffee. Also, others in your group might see your message and want to meet up with you. This would help pass the time more quickly.
Kind regards,
Olly, your editor