I'd suggest only buying food
for the first few days - plus condiments and stuff like that for the week.
You may find yourself wanted to eat out more frequently and can always stock up as you move around. Soper's Hole, Trellis Bay, Spanish Town, North Sound - all have places you can stock up on additional provisions.
I find it's better to buy things as you need it rather than and up with too much at the end of the week.