Quick tacho question

Total:
Not used any reduced days this week and I’m running out Sunday, As a new week is starts at 00.00 Sunday night if I were to use a 9 would that go onto my working week from the Monday or from the previous week ?

Thanks

reduced daily rest are max 3 BETWEEN WEEKLY RESTS not per fixed week

I blame the DVSA for some of the confusion because one of their theory questions is - how many reduced daily rests can a driver take in a WEEK ? - which refers to the fixed week which is WRONG