Since you're starting with 120 skill...
I'd be tempted to start with 50 LP, to minimize the grind.
The rest, is up to your training preferences.
The best candidate would be Remove trap, if available at character creation, as while RT gains quickly without detect hidden doing maps, I'm not sure how well the old training methods work without DH. I was able to get to about 90 RT from doing around 100 maps of the first 3 types (which, of course, you'll get LP and cart gains from as well)
Cartography trains quickly (especially if you get some Alacrity scrolls for it), but is a lot of grind with blank maps, then selling or tossing the made maps.
So, LP & RT if possible.
If RT not possible in character creation, get the hardest-to-train skill the character will be using to fight the spawn.
If I was building a new TH from scratch (where I can buy skills - SP would be a bit harder), personally, I'd do the following - but I'm an odd one when it comes to training preferences, as I find natural training through use less of a hassle than grinding.
120 points
50 LP
50 in a spawn combat skills (especially if one without a New Haven quest).
last 20 in whatever.
Buy as much cart as possible, train it to where level 1 maps are possible.
Buy the rest of the spawn combat skills needed.
train skills against things that drop Stash level maps.
Train RT, Cart and LP doing Stash maps, eventually switching to farm Ilshenar spawns of the same, where I can get supply-level chests/maps off the paragons.
In times without maps, train LP & Cart the old-fashioned way as needed, as well as other skills.