The invitation is the message you send first
The hard part of a WhatsApp invitation is not the typing. It is that a paragraph in a group chat stops being an invitation the moment someone scrolls past it. Nobody knows who read it, a cousin answers three days later with one word, and by Friday the headcount is a rumour.
My Joyfullday has a WhatsApp assistant called Jitabi for exactly this. Message the number with the shape of your event: who is being celebrated, when it happens, where. Jitabi drafts the invitation and a small event page to hold it, with a reply button guests can tap. Nothing is final on arrival โ you keep editing by replying in the same thread until it reads the way you want.
The first message does most of the work. Four details carry it: the occasion, the date, a rough time, and the place. Everything else โ the dress note, the line about gifts, the wording of the welcome โ can arrive in a second message.