The rule
When someone invites you to something, answer within a day. Yes or no, either is fine. What isn't fine is keeping them waiting while you see whether anything better comes along.
Why it matters
Behind every invitation is someone with a table to plan, food to order and a list of people to chase. A quick reply is the first kindness you can do them, and a late one is the first burden.
How to do it well
- Check your diary and reply the same day if you possibly can.
- If you need time, say so and give a date when you'll know.
- Once you've accepted, go. Dropping out because of a better offer is the one thing people remember.