How long would it take a tooth infection to effect your whole body? I've had one for some months but I'm going to get it taken care of real soon.

No time frame. You are asking a prediction as to how long your body can fight off a chronic infection, at that is impossible to do. The sooner you have the tooth restored and treated, the less chance you have of a major health problem and the loss of the tooth. Before antibiotics, tooth infections were one of the leading causes of death.
Until it does. It could be never if the infection is contained or it could takes hours if you have a virulent strain of bacteria and it gets into your bloodstream. Once in the blood stream it can spread throughout your body quickly. It's not smart to wait months with an infection and you have been very lucky so far. If i were in your shoes i would go tomorrow at the latest, and not "real soon"!