Leading in the Dark

Hey all - 

I'm an associate in PE looking ahead to the Senior Associate / VP gig. I've obviously learned a lot in my first couple years on the job but there is so much that I still don't know / haven't seen. Obviously, this is normal for everybody, however I can't help but be worried about how I'm supposed to guide a first- or second-year associate through distinct modeling questions or analyses if we run into things I've never encountered before. As a very insignificant but present example, I'm helping an associate model out a business in a segment that I've never looked at before and even things as simple as thinking through how to project things like D&A / capex in an appropriate manner take me a lot longer than for industries / companies that I'm familiar with. 

Are any current VPs and up able to share how they managed through this transition and what was most helpful? Should the mantra just be fake it till you make it here? 

Appreciate any responses!