Academy › Build › Bookings and orders

The clock you set on the reply before you call the next person

You'll come away knowing what deadline to give based on how soon the appointment is, with a cap that never climbs no matter how far off the slot is, and the exact wording that spells it out instead of leaving it hanging.

By Yodai · Published on September 6, 2026 · Updated on October 12, 2026

It's ten in the morning and someone just canceled their noon appointment. You've got an open slot in two hours. You text the first person on your waiting list: "The noon slot just opened up, does that work for you?" And there you are, staring at your phone.

Fifteen minutes go by. Then thirty. No reply. Do you text the second person now, or wait a little longer in case they're driving, in a meeting, or out of cell service? Jump too soon and you look bad to someone who was about to say yes the moment they checked their phone. Wait too long and the noon slot shows up empty, and you've lost two hours you could have used to fill it with someone else.

The deadline you give each person to respond isn't about manners. It's what decides whether that slot gets filled or stays empty.

The further out the appointment, the more time you can give

You've already decided who to notify first. What's left is deciding how long that person has to respond before you move on to the next one, and that window isn't always the same: it depends on how soon the appointment is.

If the slot is within two hours, the deadline has to be genuinely short: about thirty minutes. That's what Sutter Health, a large California healthcare network, gave for same-day slots, though the study behind it notes that giving more time might actually improve acceptance. And in the Mayo Clinic study on its medical appointment waitlist, half of all responses came in within the first 25 minutes. It's not urgency for its own sake. If the answer is yes, that person still has to make it there, and if it's no, you still need time to text the next person on the list so they can make it too. The closer the appointment, the less room for error behind the deadline.

If the slot is for the next day, you can give anywhere from one to three hours: in that same study, 65% of responses, whether yes or no, came in within the first hour, and nine out of ten within 2.7 hours. If it's more than a week out, you can go up to twelve hours, but that's the ceiling. Not one hour more. Twelve hours is what patients at the University of California, San Francisco had to accept a slot before it expired, and at Sutter Health, notices sent out in the afternoon expired at 5:30 the next morning, whether the slot was for the next day or a month out. A forty-eight-hour deadline doesn't help anyone: it just keeps the slot frozen while the rest of the list keeps waiting on an answer that's out of their hands.

Here's what happens when you turn this into a fixed rule: no matter how far off the appointment is, the deadline's ceiling never climbs. Twelve hours is the most you owe anyone, and past that, stretching the deadline only keeps the slot sitting idle. One more thing to keep in mind: in all three studies, the notice went out to several people at once, up to eight at Mayo Clinic and five at Sutter Health, and whoever accepted first got the slot. You're notifying one person at a time, so a long deadline slows you down even more than it slowed them.

Give an exact time, not "whenever you can"

The deadline is useless if you don't say it out loud. "Let me know when you can" isn't a deadline, it's an invitation to put it off. The message needs to spell out the exact cutoff time, based on when the appointment is. That's how Mayo Clinic does it: their notice reads, "this offer is available until today at 11:48 a.m. or until another patient accepts it."

You don't need to explain why there's a cutoff. Just state it, and say what happens if it's missed: you'll offer the slot to the next person. That's not a threat, it's the rule they already agreed to when they joined the waitlist. And if you're texting through WhatsApp, that agreement matters: WhatsApp Business's messaging policy only lets you message people who've given you their number and agreed to receive your messages, and requires you to stop messaging anyone who asks you to.

A short deadline isn't rude, it's necessary

There's one case where the deadline gets trickier: when the notice goes out outside business hours, at night or on a weekend. If you send a message at 10:00 PM for a 9:00 AM slot, you can't give twenty-four hours, and you can't just say "answer whenever you get a chance" either, since that person might be asleep, and so might you. Set the cutoff for a time when you're both likely to be awake, say 7:30 AM, so you still have real time to reach the next person before the day gets going. Sutter Health and Mayo Clinic did something similar: notices sent out in the afternoon expired first thing the next morning.

At bottom, the deadline doesn't measure how long it takes the other person to read the message. It measures how much time you need afterward, so that if they say no, you still have time to try someone else before the slot slips away.

Once the deadline is set, every open slot has a clock running from the moment you offer it. What you do when that deadline passes in silence, or when the answer is a flat no, is what the next lesson covers.

But once the deadline passes and they say no, don't just take them off the list: some no's just mean "not this time," and some mean "remove me."

In Yodai your clients request a time on your site and you confirm it from your dashboard. See how online booking for your business works.