They can partially fill subsequent ponds and achieve higher...

They can partially fill subsequent ponds and achieve higher salinity as the rate of evaporation is linked to surface areas.

Assuming the sea water is 35grams/ litre, Logically, if pond 1 was 2m deep and lost 0.5m through evaporation and pond 2 was only filled to 1m deep and lost 0.5m then the salt content of pond 1 would be 35grams per 0.75 litres (abt 47grams/l) whereas pond 2 would be 35grams per 0.5litres (abt 70grams/l). IMO they will already be thinking about adjusting filling sequence to recover some of the lost time. Of course they will be limited by what they can do but they will probably not fill one pond at a time imo. In theory they could partially fill all the ponds if they wanted to but I suspect approvals will prevent that.