The overnight coach is one of the region's best kept travel habits. You board in the evening, you sleep or half sleep through the dark stretch, and you step off in another country as the cafes are opening. You have saved a night in a hotel and gained a whole day at your destination. The only catch is that a timetable which crosses midnight is genuinely easy to misread, and misreading it is how people end up at the station a day early or, worse, a day late.
A coach that leaves at eleven at night and arrives at seven in the morning has not travelled for minus four hours. It has travelled for eight, and it arrives the following calendar day. That sounds obvious written down, but on a busy results page with a dozen departures it is exactly the detail that slips. We do three things to make it hard to get wrong. The duration is shown as its own figure, so you never have to subtract clock times in your head. An arrival that falls on the next day carries a small marker next to it. And the date shown against the arrival is the arrival's own date, not the departure's.
When you book, the date you choose is always the departure date. If you need to be somewhere on a Friday morning, you are looking for a coach that departs on Thursday night. That is the single most common thing to get backwards, and it is worth saying twice.
Honestly, it depends on the coach, and this is where the amenities we list matter more than usual. Reclining seats, a toilet on board and air conditioning turn eight hours into something you can actually rest through. Wifi is nice but you will probably be asleep. If the route offers seat selection, the small fee for a window seat away from the toilet is money well spent at night. Bring a layer, because coaches run cool, and something to eat, because the stops are few and the hours are odd.
Border crossings happen whenever they happen, which on a night coach often means being woken at two in the morning to hand over a passport. It is a small price for waking up in Thessaloniki or Belgrade, but knowing it is coming makes it less jarring.
Search for the departure date, and look for the departures in the evening. The results show you the departure time in the departure city's local time, the duration, and the arrival time and date at the other end, with the next day marker where it applies. If you are comparing a night coach with a morning one, the date strip above the results lets you flick a day either way and see the fares, because sometimes the overnight departure on Thursday is cheaper than the Friday morning one and gets you there earlier too.
Your ticket, when it arrives, repeats all of this clearly, with the date and time of departure and the stop you board at, and on the day the driver has the same list. So the only thing left to get right is to be at the station on the evening you chose, a little early, with a jumper.