Hi Bob,
I would recommend you to incorporate DA also in the same way because a newly created page will have relatively low page authority but will benefit from the higher domain authority of the entire domain, so may still be ranked fairly well while it builds up its own page authority.
Domain Authority predicts how well a page ranks on a domain, the higher the Domain Authority, the better chance there is for an individual page on that domain to rank highly. Page Authority predicts the likelihood of an individual page ranking well, no matter what the content on the page is. The higher the Page Authority is, the more likely it is that the page will rank.
So, DA should also be incorporated.