Hi,
Firstly, congratulations on the start of your diet journey.
Until you reach ketosis you do feel pretty lousy (usually day 4 or 5). The first week is the worst I promise you.
Take your usual headache remedy and drink plenty of water. You will need to find distractions so you don't think about the hunger - read a book, have a bath, go for a walk etc.
Good luck - I'm sure the scales will show the rewards at your first WI