First Word Anxiety

It's been a little over a week since I finished Valley of the Dying Sun, sequel to The Rise of the Synija. I read VOTDS in about five days, and was so excited about how good it was! It needs a little polishing, but overall I'm happy with the way it turned out. Now it's time to put it away and let other people read through it and give me feedback.
Which gives me the time to turn my attention to the third book, Temple of Ten Thousand Bones (tentative title). But I'm finding a strange resistance to beginning a new book. It's as if I'm having difficulty letting go of my second book. It's been so long since I've worked on another book. I'm still in shock that it's finished. How do you move on to a new love, after loving this one for so long? Yes, it's still the same story. I imagined that I wouldn't be able to wait to write that first word on my third book in the Synija series. Yet, it's a threshold that I don't feel ready to cross.
Lately I've been contemplating the past and the future. It seems so many people want to change the past, but they accept that their future is set in stone. They are doomed to fail at their business, make their parents' mistakes, or be alone forever. Yet they obsess about past mistakes, wishing they could go back in time and change them. It is not the past we should want to change, but the future. And in order to change the future, we must accept the past.
This reminds me of starting on my third book. In order to move on with the story, I have to accept my second book- the past- as it is, and have the courage to move on. I did enjoy writing my second book, Valley of the Dying Sun. I could spend another decade trying to make it perfect, changing things and adding scenes, but the story would never progress.
I feel that everything has to be perfect before I can start my third book. As if there is some ceremony I must attend, some rite of passage. But in reality, right now is as good a time as any. And it's time to move on. Let the past be the past, and move forward into the future. Write the first word....