In international business, a good general rule is:
A.
Strive to get to know coworkers and quickly get on a first-name basis.
B.
Be aware that most other countries are much less formal (than the U.S.).
C.
Address people using their formal title until they invite you to talk to them on a first-name basis.
D.
Follow your own customs, no matter what country you are in, because people don't expect foreigners to know their cultural rules.