Most published send-time guidance is email research wearing a different hat. Email sits in a queue and gets processed later, so timing shifts open rates. Messaging gets read within minutes almost regardless of when it arrives — which means the question is not when people are receptive, but when the message is *useful*.
The legal guardrails come first
9am to 8pm, in their timezone
The US federal baseline is no earlier than 8am and no later than 9pm local to the recipient, and several states are stricter. The conservative 9-to-8 window keeps you inside all of them. Store the customer's timezone explicitly — inferring it from area code has been unreliable since number portability, and a 6am text is both a violation and an instant block.
Then trigger on the event
| Message | Send at | Why then |
|---|---|---|
| Booking confirmation | Immediately | Anchors it while intent is high |
| Appointment reminder | 5–7pm the evening before | People are looking at tomorrow |
| Review request | 30–90 min after the job | The goodwill window is short and closes |
| Lead response | Under 60 seconds | You are competing with four other businesses |
| Waitlist or cancellation | Instantly, for today only | Perishable by definition |
| Status update | At the state change | The point is that they did not have to ask |
| Rebooking | At the treatment interval | Clinically or practically due |
Notice that only one row names a clock time. The evening-before reminder is the exception because there is no natural event to trigger on — the appointment is tomorrow and you are choosing a moment. Everything else has a real trigger, and the trigger beats any time-of-day optimization you could run.
Times that are reliably wrong
- Before 9am. Legal risk plus the message gets buried under overnight notifications.
- Monday 9am. Competing with the week's entire inbox backlog.
- Friday after 4pm. Anything needing a response now waits until Monday, and reads as urgent when it is not.
- During a scheduled commitment you know about. If they attend your 6:30am class, do not message at 6:30am.
- Weekends, for anything non-urgent. iMessage is a personal space; the weekend is more personal still.
How to actually find your window
You do not need a study. You need four weeks of your own data, split by hour, watching the delivered-to-read gap and the reply rate. That comparison tells you far more than any industry benchmark, because it is measured on your customers.
If read rate is high but replies are low, timing is fine and the message is wrong. If read rate is low, move the send. That diagnostic split is the main practical use of read receipts.