I love DPNs! Keep in mind for the future that if you are not completely happy working with them, there’s always magic loop and 2 circulars.
Glad you’re not having trouble with ladders at every join, just once a round. I say try knitting every first stitch of a round super-tight to fix that. And your cast-on tail can be used later to sew up the gap. I promise that very soon you will stop feeling like you have not enough hands/fingers, and too many needles.
There are a couple of ways I’ve heard to prevent this occurring in the first few rounds: some people cast on an extra stitch, and when they join and are about to knit the first stitch of the cast-on round, add the first stitch from the other end of the cast-on, and knit those two together.
I’ve tried it and I find this way much better: switch the first and last stitch when you are joining the cast-on row into a round., so they take each other’s places, with one of them going through the other stitch. Crochet hook very helpful here. Pull both strands tight as you knit the first few stitches.
Also, make sure you use a proper slipknot when you make the first stitch as you cast on, not just any knot. You can find instructions for this on the net, probably also on one of the knittinghelp videos.
When you do this, pulling on one strand will tighten the knot, and one strand will loosen it. PLEASE MAKE SURE that it is the TAIL that tightens the knot, NOT the end going to the ball, otherwise the first stitch will get irreversibly loose and floppy. Then tighten the stitch by tugging on the tail.
Doing both of these gives me a completely invisible join, and when I weave in the end later, I make a stitch or two that looks like a cast-on stitch, so you don’t see an interruption. It’s completely invisible.
Having said that, no-one’s likely to notice, so don’t fuss over anything that won’t bother you. Congratulations on learning a new technique. I personally have a fetish for lace socks. Hope you’ll join me now that you can do socks.