The alarm goes off at 5:15 a.m. Sargi is already on the table because one of you packed it the night before. That single decision, doing the preparation on Wednesday evening instead of Thursday morning, is where most working Karva Chauth plans either hold or fall apart.
Chanakya wrote in the Arthashastra that preparation done before the moment of need is the only preparation that counts. Applied to a Thursday fast: everything that can move to Wednesday night should move to Wednesday night.
