vitrectomy recovery - what to expect ?

I got surgery done in my left eye 2 days ago with a bubble placed in the eye. I am seeing flickering lights along the peripheral visions. Is that normal during recovery? I am asked to keep head down "all time". What does that mean? can I lift head to do a momentary chore? What all and how much can I do that requires lifting the head? How long does it take for the bubble to disappear? Thanks in advance.