An attempt to remove the Dalmore oil rig may take place on Monday.
Salvors will decide on Sunday if they would tow off the stricken platform before the high spring tides subside early next week.
Tuesday may be another option while tides look unfavourable from midweek.
Refloating stricken rig decision to be taken
20 August 2016
A spokeswoman for the Maritime and Coastguard Agency said: "A decision will be made tomorrow morning as to whether the operation to refloat the rig will commence within the next 48 hours."
Preparations continue to refloat Transocean Winner, which is stuck on rocks on the west coast of Lewis.
Some 53 tonnes of diesel spilled into the sea when two storage tanks ruptured when the rig grounded. The remaining 227 tonnes was pumped from the base of the rig to main deck tanks on Saturday. That recovered oil is being transferred onto the supply vessel, MV Olympic Orion.
Quantities of drilling mud -
A small quantity of diesel will be retained on board to supply the emergency generator and other essential services.
Further equipment for the refloat operation was placed on the rig on Friday and Saturday.
The temporary exclusion zone is due to be extended to 500 metres to seaward when
a tow-