Your invitation needs three things: the word RSVP, how to respond, and a deadline. Be warm but unambiguous. Drop-in lines:
"Kindly reply by August 15." "RSVP by August 15 — we can't wait to celebrate with you." "Please let us know if you can join us by the 15th of August."
For formal cards: "The favour of a reply is requested by the fifteenth of August." Always set the deadline three to four weeks before the event so you have time to finalize catering and seating. State exactly how to respond (link, card, phone) and avoid vague phrasing like "let us know soon," which guarantees stragglers and a stressful final week.
