Keep one pinned message that points at the three things the group exists for, and three things it doesn't. Half of the moderation work in any Telegram group is people who joined under a different assumption — a price chat, a feature-request forum, a support inbox — and the pinned message is the cheapest way to redirect them before they turn into a thread.
Run a single weekly AMA thread. Same day, same time, same pinned pattern every week — Friday afternoon works well because it catches the people who have been thinking about your app all week and haven't asked yet. The AMA's real job is not answering questions; it is making a backlog of unanswered questions visible so you can ship against the top of it.
Triage 30 minutes a day, three rules. First, anything that mentions money, security, or a refund: escalate immediately, never answer inline. Second, anything that is a real bug report: copy it to your tracker and reply with the tracker link, not a fix timeline. Third, anything that argues between two members: pin a one-line ruling and mute the thread for the day. Almost everything else can sit until the AMA.
Read three signals, not all of them. Daily active members (the people who sent a message in the last 24 hours), message-to-member ratio (the average number of messages per active member per week — a healthy group is around 4 to 8, below 2 is a ghost town, above 20 is drama), and the share of the week's conversation that came from you. If that last number is above 30 percent, you are doing too much — your community does not yet have any other voices and that is a liability.
Finally, accept that the first thousand members will be the most expensive to steward and the least loyal. The second thousand will talk to each other. The point of the early rhythm is to survive until the second thousand.