You should be fine using just one of those mason jars for your starter. I usually start with 1000ml of fresh wort and then decant the liquid off the top of the starter. Leave a little bit of liquid still in the mason jar and swirl it good to get all of the yeast off the bottom and into suspension. Then, just dump that into your starter wort. Your four washed jars should last you at least 3 brews, if not four.