In reply to TheseKnivesMan: If you see bouldering as training, then I would say the grade you need to start training at is about Vdiff.
I started climbing by leading HS/VS grit routes. I got up to soft HVS by just climbing routes, indoors and out. When I started bouldering, I developed finger strength and technique for doing hard moves, not just moving eficiently. It became immediately apparent that the holds on VSs are enormous, because I could use tiny crimps and nothing-slopers on boulders after a bit of practice. Very helpful if you want to climb E-grades.
As for pull-ups, finger boards etc for strength: you can get pretty good just by bouldering, so I don't really see the point unless you're at about font 7a and can't get stronger/better just by climbing more (probably due to lack of time doing it). I would suggest that below that grade or thereabouts, the time spent on training rather would have been better spent bouldering because it would improve technique and exactly the right kind/balance of strength in every area of the body. Training might be a quicker way to improve though, but I've met alot of climbers who do that who can climb overhanging boulder problems with decent holds (up to font 7b or so) but who can't climb a 6b slab or arete. That's called crap footwork.
As you can probably tell, I'm not expert on this stuff and have only just started training for climbing (before now, I've just gone to the indoor bouldering wall aimlessly over winter). I'm doing lots of laps on routes rather than strength training, because all the bouldering I've done over the years means I've got the strength and technique I need to climb harder, but I need to be able to use it when pumped out of my box.
But everyone's different - if your weakness is finger strength but your technique flawless, then finger boarding might be the best way forward. That could be at any grade I suppose (although I think it would be hard to develop flawless technique without climbing at least french 6b).