In the best case scenario, after cold crashing your starter for 24-48 hrs you should be pitching it into your chilled wort. Don't forget to allow it to warm up a bit out of the fridge, but ideally you want to pitch a few degrees colder yeast into your wort. Sanitize the opening of the growler and carefully decant most of the wort except for a small amount that will help you swirl up the yeast cake into suspension. Then resanitize (yes, I am anal) the opening again, and pour your yeast into your chilled wort.
Nice job making a starter as that goes a long way for improving the quality of your beers...