Does anyone experience a lag time before they experience the onset of their symptoms?

Last week I felt quite good, and pushed my self more than I have in a couple years . On Thursday, I felt comfortable enough to ride the exercise bike for an hour or so and use some machines at the gym. However, I started to feel worse the following evening and much worse on Saturday.

So do any of you experience this lag, or do you mainly feel crummy right doing something strenuous?

For me it's a bit of both. However, if I already feel crummy, I am more likely to be affected immediately after or while doing something.