Check the Normal SOP section in the FCOM.
It should be written in the preliminary cockpit preparation section whether or not you should keep the dome light in dim for take-off.
This was written in the 2012 FCOM version:
DOME light should be on because it is the only lighting source in the EMER ELEC configuration. The DIM position is recommended for takeoff.
If this isn't written in the current FCOM, it's no longer required.