Why does my Touring Plan have me arrive outside of my FastPass+ window?

With a FastPass+ reservation, you officially have a fixed time window (for rides, it usually lasts 1 hour) in which arrive at the attraction.

Unofficially, however, Disney allows entry up to 5 minutes before the start of the window and 15 minutes after the end of it. The optimizer is programmed to know this, so it will occasionally have you arrive a few minutes early or late.

Note that you do not need to apologize to a Cast Member or do anything special us this "grace period": simply arrive up to 5 minutes early or 15 minutes late and tap your Magic Band or ticket, as usual.