To answer your question: it is hard to say if or when you will come down with the flu. Depends on how healthy you are, the infection's incubation period, and how good you are at hygiene.
Good hygiene:
Wash your hands regularly with soap and hot water.
Keep your hands away from your eyes and mouth.
Do not put foreign objects, for example pens, in your mouth.
Use some sort of disinfectant to wipe down common use areas, phone kitchen, etc that you have with him.