Picture the private room at that local bistro on a Saturday morning, with the coffee pouring and everyone celebrating together. Pulling this off without a scramble starts with the calendar, since locking in that space three months in advance gives you the breathing room you need.
Bridal showers come with fixed deadlines, meaning lead-time is your real leverage. You want to book the venue early while the date is open, leave the menu details for later, and keep a close eye on the total so nothing sneaks up on you.
That 18-month window is a hard deadline, not free money, and any leftover balance when it ends will start collecting standard interest.