Zenless Zone Zero: “Ding-Dong!” caps at 2 Wish Letters per day — the schedule to follow from August 28 to September 14 to collect everything

HoYoverse detailed on Wednesday, August 26, 2026 the "Ding-Dong! Delivery Training in Progress" event in Zenless Zone Zero. It runs from 08/28/2026 at 10:00 to 09/14/2026 at 03:59, server time.

The premise fits in one sentence: help the Bangboo deliver wish letters, and cash in Polychrome once a certain number of deliveries have been made. What warrants a guide is how these letters are earned — because it makes catching up impossible.

Two letters a day, not one more

HoYoverse is precise:

"During the event, you can obtain 1 Wish Letter upon your first login of the day and upon your first use of Battery each day, for a maximum of 2 per day."

So there's no way to speed things up: not by playing longer, and not by spending more Battery. The two sources are independent of each other, and each triggers once per day.

A simple login isn't enough to get the full amount: you also need to spend Battery every day. That's the easiest mistake to make during an eighteen-day event.

The math to do, starting now

The window runs from August 28 at 10:00 to September 14 at 03:59, server time. The last day on which both daily sources can be triggered is therefore September 13, since the reset on the 14th falls after the event closes.

That makes 17 usable days, or 34 wish letters at most. Every missed day costs two letters, and there's no way to make them up. If the event's reward tiers require a total close to this cap — HoYoverse doesn't publish the thresholds in its announcement — a week's absence is enough to lock the top tier out of reach.

Access requirements: level 20 and the Chapter 1 Interlude

Two conditions, both reached early on:

• Inter-Knot Lv. 20;
• having completed the Chapter 1 Interlude of the main story.

An account that has followed the campaign past the first few hours meets both without effort. There is no requirement tied to version 3.1.

Where to deliver: Batti, in Booastrum

Letters are dropped off with Batti, in Booastrum. That's the event's only interaction point: everything else plays out in the daily routine.

Nothing requires delivering right away — the announcement doesn't mention any intermediate deadline. But nothing encourages waiting either: it's best to clear your stock as you go so as not to forget a batch on the evening of September 13.

The event spans the end of 3.1

A calendar detail that doesn't appear in the announcement and is worth pointing out: version 3.1 "Long Farewells" ends on September 8, while "Ding-Dong!" runs until the 14th. The event spans the version switch.

In practical terms, this means two things. First, the daily routine you need to keep up doesn't stop when 3.1 closes its other activities. Second, update maintenance usually takes up several hours: if it falls during your usual play window, plan to check back afterward so you don't lose that day's two letters.

What the announcement doesn't specify

HoYoverse says that Polychrome drop "after delivering a certain number of wish letters," without publishing the thresholds. This has two consequences:

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• It's impossible to calculate a minimum target today. You'll need to open the interface on August 28 to see the thresholds and know how many days are actually needed.
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• The cap of 34 letters is an upper bound, not a requirement. If the last threshold falls at 20 deliveries, missing about ten days is still recoverable; if it falls at 34, there's no margin at all.
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Until this number is known, the only no-regret strategy is to treat the event as if it required the cap.

A login event, not a content event

Let's be clear: "Ding-Dong!" adds no combat, no zone, no mode. It's a retention mechanism, built on two daily actions that most players already perform — logging in and spending battery.

This changes how you should prioritize it. It requires no preparation: no character to level up, no resource to set aside, no team to build. Its only requirement is consistency, and that's also the easiest thing to break over seventeen straight days.

Conversely, a player returning to Zenless Zone Zero after a break has every reason to start on the 28th: two low-bar conditions, no version prerequisite, and Polychrome for a two-minute daily routine.

The routine to set up

1. August 28, 10 a.m. — open the event and talk to Batti for the first time.
2. Every day — log in (1 letter) and spend battery at least once (1 letter). Both, not just one or the other.
3. September 8 — version switch day: come back after maintenance.
4. September 13 — last useful day. Deliver everything remaining before the closure on the 14th at 3:59 a.m.

Times are server times, as published by HoYoverse. Event, location, and character names are copied from the official announcement.