Ask HN: How open should I be about finding other clients?

I started my own software company this year (long time dream of mine realized!). It's currently just myself on an open-ended full-time contract as a developer for one client, but I am going to be expanding to multiple clients and hopefully hiring more developers soon too.

My agency and client both know that I'm billing under a corporate name, but it's just me working full-time for client #1. I have no intention of ending this contract (it is a great gig and about 95% of my projected income), but I do intend to take some time out here and there to grow my new company (meetings with new clients, traveling, networking events, etc) when appropriate. Maybe a few hours here and there, a full day every once in a while. About as much as I would have taken vacation at a FTE job.

How open should I be about my dual role as software developer and business owner? Should I just call it vacation time when I need to devote some daytime hours to other clients? Or should I just be completely open and transparent?