Arrival and check-in will likely be on the first day of the session. We just need to confirm the dates. I think starting on the 3rd would be perfect.
If anyone arrives at night or early in the morning, I can meet them at the train station. I live a 10-minute walk from the Central Station and a 20-minute walk from the Southern Station (they are located next to each other and connected by passageways). The shuttle from Boryspil (airport) also arrives at the Southern train station and runs 24/7.

And yes, you should buy tickets now if you don't want to hitchhike to get here)).