How Many "Trips" to Register Sensor Emissions Data?

Question: how many "trips" (which from reading the FSM I think means cold-to-fully warmed up starts) does it take to get the OBDII system to record values for things like the catalyst?

Background: My XJ is currently showing several emissions values as "n/a" or empty. State vehicle inspection is coming up.

I had to replace the battery in my 2000 XJ two weeks ago. I knew this was likely to re-set the emissions values in the OBDII system, and it did. Several of the sensor values have still not reset, though. (I don't drive it much - typically once or twice a week, because I commute by foot and train.) This is getting to be a bit of a concern because the vehicle is due for inspection soon and from past experience with another vehicle I know the state will reject the vehicle if the emissions tests don't pass because of insufficient/empty data values.

There's a big discussion in the FSM about what constitutes a "trip" but no #s given about how many trips are needed to store all the required data after the system completely resets due to a battery change.

Any help appreciated. I guess I just gotta drive more often... :roll:

Ive always been told around 50 miles of driving will get the computer back on track.
Weather thats in one run or several I'm not sure.