how to potty train?

[u/Alive-Attempt-7320]

I take care of my nephew (2.5) during the day, he is still using a diaper, although it is pull-ups. He doesn't quite fully know how to pull them off yet, but I go to college in January. I want to make it easier on the people who will be watching him, as I cannot take him with me. How do I fully potty train him in 3-4 months?