Before I had a kid, I wanted to compare seeing the proof copies of your book to seeing a child for the first time — but nothing can compare to the joy of holding a new life. That being said, holding a new book is still pretty cool.
But the joy of seeing your book printed is more like sending your kid off to college. You have done everything you can to prepare them for the real world (writing, editing, cover design, copyrighting, legal paperwork, beta readers, etc) — now it’s time to see what they’re made of…. and hope they’ll stop costing you so much money soon!