Short answer
Early enough to be read before the visitor types anything — the requirement is "at the latest at the time of the first interaction". In practice that means the greeting shown when the window opens, not a line that appears after the first question.
Why that is
Paragraph 5 is worded in time, not in position; the regulation prescribes no place in the window. But a disclosure that first shows up in the third message arrives later than the first interaction, which leaves the greeting as the one spot that meets the requirement without argument. A label in the widget header is a useful addition, though it is often truncated on narrow screens. Our measurement is deliberately generous here: P2 searches the entire visible text of the opened window, embedded frames included, and reports "found" or "not found" — never "in the wrong place". Judging placement would be a legal assessment, and we do not make one.
This is measured in check point P2 — AI disclosure inside the chat (Art. 50 Abs. 1).
What this means in practice
Open your own widget the way a stranger would, ideally in a private browser window so no earlier session resumes and the bot really starts from the beginning. Then read what is visible before you type anything. If the AI disclosure is not there, edit the greeting message in your provider's admin area — not the answer templates, which only apply later. Check the auto-open case too: if the widget pops up by itself after a few seconds, that popup is the first interaction.
Check it on your own page
The check performs exactly that manual step automatically: open the widget, read the visible text, report what was in it. If the window could not be opened, we report that instead — an unopened window is not a missing disclosure.
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Legal note
This page provides general information on the EU AI Act — it is not legal advice and not a legal assessment of your individual situation (cf. German Federal Court of Justice, judgment of 9 September 2021, I ZR 113/20). It does not replace review by a lawyer. When in doubt, consult one.