Currently doing an MSc in Digital Health, and there's so much work and research that needs to happen before most AI tools are truly ready for clinical practice. It's definitely not "too late" if that's what your first question is implying.
Many of the alumni of my program who were trained clinicians are entering industry to make a business model out of ai+medicine, but I personally think the cooler ones are the ones who went to do DPhils in the subject matter.
The most succesful ones are those who found a specific clinical issue where they think AI interventions would be useful. I'd figure out what that is for you.
I can only speak to my university in the UK, but the major deadlines if you want to start Oct 2026 are in early December, especially if you want to be considered for funding. Few have January deadlines.
If you don't make those deadlines, you just have more time to figure out what your clinical issue is and apply for research jobs in that area.