of course — It is much less uncomfortable to check with Dor Yeshorim before going out altogether than after a 4th date. Initially it is clear that this is just part of your checking, as opposed to once you start going out the “other side” can be reading all sorts of things into it (“does this mean she/he thinks it’s serious?” “maybe we’re not holding at the same point”, etc.)
As has been mentioned earlier — it is a VERY EASY thing to do!!! Why risk being put into an uncomfortable situation at the least, and possibly a heartbreaking one? Dor Yeshorim themselves in all their literature practically begs everyone to check BEFORE starting to date.