Average time and best technique for preparation

Agreed, probably not the best place for i, but here it goes.
I don't think postponing intern year is good for anyone, just get it over with already! But you definitely do need dedicated time off (at least 1 month) before the test. So my advice would be, study during intern year and take the test 1-2 months after you finish. Or if you are sure you can get time off during intern year, take the test then. Just do 1-2 NBMEs before the actual test to make sure you're ready.