I had answered this a long time ago:
FROM OPERATIONAL LIAISON MEETING FBW
7Safety Precautions ...
The Flight Control check to be done prior to autobrake arming:
If the spoilers are left in the extended position after landing...
the aircraft will suddenly brake at autobrake MAX arming!!!
Recommendation introduced in the SOP.
For Approach and landing it can be selected in approach preparation and briefing and the selection is confirmed at gear down. Also at flap3 selection.