The big first week losses are due to loss of water bound up by the glycogen. If you were eating low carb ( but enough to maintain yr starting weight), your first week will be a regular vlcd weekly loss - not the larger starting loss many have.
I am starting a similar plan from tomorrow , it has been complicated for me to find motivation. I already did it in the past , what I know is sometimes you have some period when you lost less, what works for me is eating « white », it really give me a push in that case: cauliflower, fennel, and fish or chicken. For vegetables white or green are perfect. Hope it helps.