Individual ship routings are not public, wouldn't
do much good anyway. Airlines swap aircraft on
and off for many reasons - late inbound, out of
service, maint delay, equipment onboard,
The airline tracks it in order to position the
aircraft for mechanical servicing and other
things as well.
A desired routing will be dropped to keep the
schedule running on time if possible.
I've had as many as 4 different ships assigned
in a one hour period during a extensively
delayed flight. The aircraft routing display isn't
a high priority function and often lags the
real world by hours.
So to answer your question... At the start of
the day most airlines have a good "guess" as
to what will be where, by the end of the day
it will be anyone's "guess". (grin)