First of all let me say good luck! I just got my TLPD this weekend finally, and I have a thread here about it if you havn't already seen it.. I kept track of spawn times etc. so maybe it could help you get an idea.
In my experience Vyra spawns can be as early as 2 hours and as far as nearly 20 hours apart. I believe the TLPD has a very small chance to spawn instead of Vyragosa; I'm thinking way lower than 20%, maybe as low as 5%, which is why there can be weeks without a spawn. Whats unusual about when I got my TLPD is that it was spotted 4 confirmed times in a week, three of which were in three days.
Friday: 11:58am
Saturday: 11:30pm
Sunday: 11:48am
You can see the pattern in mine.
Regarding other rares being up: Its just a theory, and it's 3-5 rares up at a time. Don't leave storm peaks to kill rares! Camp camp camp. A friend was camping a second spawn for me, left to kill rares, and less than 10 minutes later TLPD spawned at the point she was watching and I missed it as I was not on that path. Stay in Storm Peaks! If you must, see if you can get another friend to travel and look for them and murder them.
I also recommend setting up a rig to stay logged in game with NPCscan running while you are asleep! There are two ways that I know of to do this.
1. Set up an analog clock with a second hand; take the face off it and tape an inch wide piece of paper etc. to the second hand, making it wide enough and close enough to the glass to be visible by a laser mouse when it goes by. Replace the glass. Have something heavy and small (I used batteries, and a friend used a roll of dimes) to tape to your left mouse button to keep it pressed down. Set up your mouse on the clock with the button pressed down, make sure your camera twitches when the second hand goes around, and voila!
2. This is easier but it involves white noise and I havn't actually tried it myself. Get a piece of paper, place your laser mouse on it, and use a fan to blow on the paper, causing it to vibrate and keep your laser always moving.
Its very helpful to get an extra 8-10 hours camping in while sleeping. I rode on my HH mount (so it didn't have noise), turned down my music and ambience, and had sound (including NPCscan) cranked! It works.
