Scheduled campaign sent at the wrong time — timezone issue?

Almost certainly a timezone mismatch — scheduling uses whatever timezone is set on your account under Settings > General, not your browser's local timezone automatically. If that's set to UTC (the default for new accounts) and you're expecting your local time, that would explain roughly this kind of gap depending on your offset. Worth double checking that setting matches where you actually are, and future scheduled sends should line up correctly after that.