After adding new contacts to a group in Gmail Contacts, an email sent to that group will be missing the recently added contacts, with no alert to that fact. You can check the emails to see if they're missing, but with hundreds in a group that's not really feasible, so I end up waiting many hours or a day before I dare send a message.
I don't expect anyone here to fix their bug, but I hope someone can tell me what the amount of time that I need to wait to be safe is.
So,
How long do I need to wait before sending a message in Gmail to a group that I've just added contacts to?