Punctuality is one of those things that quietly divides the world into two camps. In countries like Germany, Switzerland, Japan and Singapore, being on time means being slightly early, and even five minutes late to a business meeting requires an apology. In much of South Asia, Latin America, Africa and the Middle East, time is more elastic socially, and a dinner invitation for eight often really means half past eight or later.
The safe rule for newcomers: be punctual for anything professional, official or transactional everywhere, including visa appointments, job interviews, trains and doctors. Government offices in particular will not wait for you even in relaxed cultures.
For social events, ask a local friend or colleague what is actually expected, because arriving exactly on time to a house party in some cultures can catch the host still cooking. Once you have lived somewhere a few months you absorb the local rhythm naturally, but until then, erring on the punctual side rarely hurts you.