MBB - PE HH Email Response

I know people who've used both approaches (i.e., ignoring vs. explicitly telling HHs that they're sitting out). I don't think it really matters. If you don't meet / communicate with them, you won't get invited to interviews through them. If you later express interest in recruiting (say after a year) and meet / talk to them then, they will actively look to place you then assuming you don't mess up your screen / have a piss poor review. 

HHs are used to getting ignored and already have to deal with hundreds of other candidates actively recruiting anyway, so feels like something not worth sweating about.  The only thing to consider is that you might stop getting emails about opportunities from that HH if you tell them you're not interested for the next year so there's some small, albeit non-zero chance you miss an opening at your dream fund that might come up in the interim / could potentially sway your mind to recruit. But that's so unlikely.

If you're confident you're not recruiting now, I don't think you lose anything by telling them you're interested in PE but now is the right time.  I'm not sure if they'll check in on you beforehand but worth being proactive and reaching out X months later to tell them you're starting to get serious about recruiting.