Let's say a group of friends from different countries are in a Skype call. For me, perhaps it's morning, while others are in midday or nighttime hours in their respective countries.
When in a one-on-one chat, I'm aware it's best to use the correct greeting for your recipient's time zone. However, this quickly gets more complicated when you have multiple recipients in varying time zones and times of day.
As someone joining this theoretical group conversation, how can I say hello without sounding strange to anyone? Is it best to use something like こんにちは? Should I use the greeting for my own time zone? Or, is there some other way I should greet the group?