Maybe I am too German, but if I agree with host that I am there at 11:30, I will be there at 11:20 and wait, be it rain, be it shine 
At the same time with most hosts we agree on which train I will be taking, and then it is in the hands of DeutscheBahn [train company] if I make it, which we both understand. I´ll text the host once I am at the closest train station, and they mentally prepare for my arrival as fast as the public transport does it.
I do respect the exact times, and I am not bothered by them. I am awkward socially, so I dont want someone coming surprisingly early or late. I need to get to the mind space. At the same time I have done as long as 3 day handovers if needed.
I recently read a review left to a sitter. Host docket stars because the sitter was 1h late, and their day plans were compromised due to this. Sitter responded that they were only 30 mins late, and it was due to an issue with their child that was unavoidable. I think hosts should have plan b for the arrival, and should not put it on the sitter if their plans fall trough - I think up to one hour lateness or earliness is normal, as we are in transport and anything can happen. With one hour buffer the host can also leave their home as soon as the handover is done, and are not left with hours and hours to waste before they can start their trip.
I recently did a sit where during the video call the host said that they leave at 4 am, and I can arrive any time during the day. The day before the sit, at 3pm, I receive a message “we are about to leave, you can arrive any time tomorrow”. Now I am left to wonder if I misunderstood the 4am/pm in the call, or if their plans changed a lot Well, at least the cat was fine. …I had secured a one night sit for the previous night, and would have appreciated if they let me know earlier, so that I would have just arrived earlier. But the one night sit was magical, so no hard feelings. Just to show that communication about times is really not “clear expectations”, no matter what one does.