I've heard of authors holding onto their subsequent books as a matter of timing, wanting to keep their audiences interested. Apparently, too many books released too soon could be problematic to keeping their fan base alive. I have wondered about this regarding my own books-to-be, as well.
As to Echoes, it was a matter of keeping an eye on the readership climate. For many, many years, my work was considered passe and out of it's time. Prose was dominating the printing presses and open mike readings when I first learned my craft. Until now, there didn't appear to be an interest in poems that rhyme, and the like.
Echoes went to print as soon as it became apparent that there might be an audience for it: namely those who enjoy the Steampunk genre. It took the obvious emergence of devotees to Victoriana to coax When None Command and The Train out of my "box of poetry," but at last, I felt that I could dare to share my work with those who value the Neo-Victorian mindset and all its trappings.
As to the other books I intend to publish, I will not be waiting long to do so. Echoes is a good first attempt at testing the current readership waters, and the responses I've received to this volume so far have encouraged me to share more of my work. My perception is that now is the time for poems that rhyme, and I am readying to launch on this new wave that I see looming before me.
Echoes, after all, is not a novel, and neither will my other books fit into that niche. And so, I have the freedom to publish whenever a finished volume is ready. As soon as the Clockwork Alchemy Convention is in my rearview mirror I'll set to work on a book that I'm tentatively titling Reverberations.