Early warding spots for figuring out which side the opposing jungler is starting

I've been practicing aggressive counter-jungling recently and was wondering if anyone could help me figure out the best warding spots early to figure out which side the opposing jungler is starting. Normally you can tell by the champ or which lane is slow to get lane, but if I want to try to kill the enemy jungler at level 2, I need to know whether I should start my red buff or krugs/gromp if we're on that side.