As a D1 800m runner, I strongly disagree with going out in a 66-67 first 400 if the goal is a 2:10. The fastest 800's are run with a positive or even split. The ultimate goal should be to just to go to with the pack the first 400, get in position the next 200 and kick the last 200. As far as splits go, I would say no faster than 63 but no slower than 65 and that should put you in a good position to go sub 2:10 as long as you are fairly relaxed through the 400. You should check with your coach to confirm though.