Hola Flagon -
xxx
Very simple - in a 747 (or any other airplane I have flown)...
If flaps have NOT been selected (snow on taxiways), it is impossible to make a before takeoff check-list.
That is a company policy, and was policy in 90% of companies I flew with.
On 747 Classic, the F/E reads that check-list.
He places the check list between thrust lever 2 and 3 to indicate CK-LIST needs to be completed.
Then, when ready, the PF calls for "Flaps 10 (or 20)"...
PF and PNF perform the flight controls check, after flaps are positioned.
Then PF calls for "BEFORE T/O CK-LIST"
The F/E reads the check-list - PF and/or PNF respond as appropriate (SOP)...
xxx
Note that the "FLAPS" challenge is answered by 10-10-GREEN LIGHT (or 20-20)...
Meaning - 10 (check flap lever) - 10 (check 2 flaps indicator dials) - GREEN LIGHT (leading edge).
Note finally that the 3 crewmembers respond - PF, PNF and F/E...
xxx
If at this time we want to check warning horn, PF just moves thrust levers forward.
All above is the standard Boeing AOM SOP, not an airline or personal procedure.
And despite all that, I still do TRIM-FLAPS-SPOILERS "3 killers" when cleared for T/O...
Just wanting to enjoy my retirement at the beach, not in a cemetery yet.
xxx
Happy contrails
P.S.
I have seen a better check list than Boeing (or any airplane manufacturer).
By far the BEST check list in the entire airline industry...
AA American Airlines had what they call a "mechanical check list".
Consists of a unit that was mounted on the side of their F/E panels.
Some 20 or 30 before takeoff items on the before takeoff check list.
For each one item (irrespective of the order) the F/E slides an indicator (meaning item completed).
By completing all items, check list was completed, and ready to be used in reverse.
In reverse, it becomes their approach and landing check list.
Could also be performed irrespective of a given order.
I used it on a 707 ex-AA on an ACMI contract. Was the best check list I ever saw.