Many D1 post Walk-On Stds., just like Partial and Full-Scholarship Std. - a 5:08 mile is right at the Walk-On Std. cut-line at D1 ACC Wake Forest - http://grfx.cstv.com/photos/schools/wake/sports/c-track/auto_pdf/2017-18/misc_non_event/RecruitingStandards.pdf
Yes, coaches will likely want to see those marks in Junior Year. That said, roster spots may not be available even if a Walk-On Std. is achieved, so yes best to reach out to coaches. A lot of it will depend on the level of D1 school / what Conference it is in.