Your team’s velocity will be faster from week 2 through the end of the 2nd year if you build the rapid feedback cycles provided by automated testing and CI/CD into your progress from the beginning

UNLESS your team lacks the experience to build and maintain a test suite with a high benefit-to-cost ratio, which is unfortunately the case for most teams.

In this case I don’t have any good solutions, other than choosing one’s team and teammates carefully, before starting the project.