It's been roughly one month (early August to early September) that I've engaged in a personal training sprint with self-study. During that time I've earned my PMI-ACP, PSM1 and PSM2 certifications.
Prior to the training/studying time I had used Scrum since 2006, Lean/Kanban since 2009, SAFe since 2014 and of course traditional project management longer since before all of that. All of these experiences helped to earn the certifications.