The only thing you can count on is him always spawning in a black forest and he barely spawns on the same island or continent that's your starting point

But apart from this he can spawn everywhere.
I read some stuff claiming he'd spawning in the south east somewhere but I also found him in the far west already, close to the end of the world.

A good time to look for him is once you beat moder and as soon as you have a decent boat.

Take lots of food with you and start an expedition.
Sail close to the coast around every island and check the map for a cash bag that will appear as soon as you get close to him.

Don't forget taking a portal with you.

Originally posted by stvlepore:

There are mods that show you where he is on Nexus.

you want to use a mod just for that?
If you're that desperate to find him I'd rather use the console command to spawn him.
As long as the game is still in EA I would only use mods that don't intervene to the game that much and those that are really necessary.
Otherwise there's a good chance of getting screwed after an update and using a mod that's discontinued like it happened to Valheim Plus.