Your 7pm bid boost may have started at 6pm last night. Daylight saving time ende
By Gabriel Caceros · November 3, 2026 · Curated by George's Blog
Your 7pm bid boost may have started at 6pm last night.
Daylight saving time ended on Sunday.
The clocks moved.
Shoppers moved with them.
Not every bid schedule did.
Depending on the tool, dayparting rules run on the marketplace time zone, on UTC, or on whatever the server was set to when someone built them.
If a rule runs on UTC, it now fires one hour earlier on the shopper's clock.
Same rule.
Different hour.
A supplement account we took over last year had an evening boost: +30% bids from 7pm to 10pm Eastern, built on two years of hourly CVR.
After the time change, the rule ran from 6pm to 9pm.
It boosted the weakest evening hour and missed the strongest one.
CVR inside the boosted window fell 18%.
Nine days later, someone read that as "evenings are softening" and cut the boost.
The evening had not changed.
The clock had.
The hourly report can make it worse.
If it shows a fixed time zone and you compare this week to last week by hour, the whole curve looks like it slid an hour.
It did not.
Your labels did.
And Sunday had 25 hours.
Its daily total will look a little better than it should.
This morning we ran the same check on every account:
→ Open every schedule and confirm which time zone it runs on.
→ Check when each rule actually fired yesterday versus when it was meant to.
→ Move any UTC-based rule one hour later so it lines up with shoppers again.
→ Re-label hourly reports to shopper time before any week-over-week comparison.
→ Mark Sunday, November 1 as a 25-hour day in the dashboard.
On most accounts, nothing needed to change.
On two, a midday rule was firing an hour early.
That is ten minutes of work.
Missing it is a week of wrong conclusions.
Black Friday is 25 days away.
Hourly decisions are about to get expensive.
Check the clock before you check the curve.
Then read the curve.
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