The wrong unit is a 1970 event

Vendors accept the wrong clock and still 200. Date.now() is 13 digits. Meta wants 10. Amplitude wants 13. GA4 wants 16. These pages are the unit, the window, and the late-event budget.

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Event timestamp units Timeengineers Meta CAPI event_time is Unix seconds (10 digits). Date.now() is milliseconds (13). GA4 timestamp_micros is microseconds (16). Amplitude and LinkedIn want milliseconds. PostHog, Segment, TikTok, and Braze want ISO 8601. Pinterest is seconds. Reddit CAPI v3 is milliseconds. Event time vs ingestion time TimeengineersPMs Ingestion time is when the collector got the HTTP request. Event time is when the purchase or click happened. Queues, retries, and epoch timestamps on ISO fields collapse the two. Send the time of the action, not Date.now() at drain. Attribution windows TimemarketersPMsengineers The attribution window is a report and bidding setting on the ads platform, not a pixel parameter. Changing it rewrites history in the UI. It does not change what the tag sent. View-through and click-through are those settings, not two pixels. Timezones and conversion event_time Timeengineersmarketers Unix event_time has no timezone. Your shop, your ads account, and your warehouse each have one. Converting local checkout time as if it were UTC shifts conversions by hours and can push them across the attribution window. Late conversion API events TimeengineersmarketersPMs Ads graphs drop conversion API events that arrive after a maximum age. Meta CAPI is about 7 days. Snap CAPI is also 7 days. LinkedIn CAPI is 90 days. GA4 MP backdates about 72 hours. Finance still needs the late sale. Clock skew on conversion timestamps Timeengineers event_time in the future is a bug. The usual cause is Date.now() milliseconds on a seconds field. Real NTP skew of a few minutes also happens. Platforms drop or mis-file future conversions. Count digits first. View-through vs click-through attribution TimemarketersPMsengineers Click-through credits a click. View-through credits an impression with no click, inside a (usually shorter) window. They are report settings, not two conversion tags. Mixing them in a ROAS target double-counts attention. Last-click vs data-driven attribution TimemarketersPMsengineers Last-click gives the conversion to the final paid click. Data-driven spreads credit across touches the platform observed. UTM last-click in GA4 is a third story. None of these is the pixel. They are models on top of the hits. Windows still apply.