Signed 3 year contract. Leaving after 2 years?

I'm working in the private placement investment arm of an insurance company. Deal flow is pretty good and we invest in all parts of the capital structure. From speaking to some of the older analysts, it seems like you learn 95% of everything your first two years and the third year is just coasting.

I'm a couple months in and am thinking about what's next. I want to leave after my second year bonus and go to an AM or PE shop. That'd probably mean I'll be interviewing a couple months before bonuses.

I'm not really sure how to approach my boss about this when the time comes. Bonuses are in March so I'd be actively searching sometime around dec-jan. Would I just tell my team once I secure the position? Our deal teams are pretty lean so I know if I leave, it be a big hit on everyone til they get another analyst up to speed.