Assuming the hiring manager was able to make time to go through the hiring process, it seems probable she/he would have time to support the new hire during onboarding. Instead of a meeting at the end of the first month, I’d set aside a small amount of time at the end of each week to talk about activities/thoughts/questions.
Think of onboarding as a release made up of ‘X’ one-week sprints. Your end-of-week meeting will be the demo & retrospective.
Shortening the feedback loop reduces the time the new hire’s ambiguities/questions are allowed to linger. It also helps them provide better feedback/suggestions, as their experiences will be more top-of-mind.