How quickly should simple carbs be used?

i know simple carbs or simple sugars are processed very quickly in the body and if too much is eaten will be stored into fat. i have heard however that this will happen if the carbs are not used quickly? So how quickly do these carbs have to be used? Immediatley? For instance I ate alot of raisin bran this morning...well mostly picked the raisins out lol. but the box says it contains 16 grams of sugar in a cup and the raisins are covered in sugar. I am trying to lose weight so i know this wasn't the wisest of choices but if I worked out immediatley after would it affect me . Would it be worse if i worked out later today like tonight? I know this is alot of questions in one but i am really wondering and need help thanx.