Not that this is new when hunting a target that potentially holds a killright.
It is possible to first find out if that pilot is actually online at the time when you want to begin your hunting by inviting that pilot into your fleet.
If they actually accept then you can give out which system to lurk in.
If they are offline the system will inform you of that pilot is currently offline.
Then you may go visit the locator agent to inform you where that pilot is hiding.
Less convoluted to just invite them to a friendly fire enabled corp, promising them great wealth and low tax, then you can see where they are in real-time as well as their online status.
Killrights seem kind of backwards to me so I never did any.
However…
Since I can add the pilot to my contact list (and I have 30 days correct?) I watch for online times. Then I could use several methods to bait them to a location.
PM from me to them; “Hey there killer! I still have your stuff here in station X, drop in so I can trade it off to you! Thanks.” confirm the message, then radio silence. Swap to your combat alt and wait for them to approach the station.
Might be worth a try, I guess. I decline all but chat invitations, and within those I am…stilted, to say the least. The inviter usually bails at the first opportunity!
Look up the average activity times of target on zkill, pay your friendly locator agent during such an activity time, and hope for the best ? Not much else to do without a watchlist, except infiltrate his corp with an alt and see who’s on corp chat, lol.