About all you can do is ask your local experts as to when the leaf miner moths start their spring and fall flights. Then spray regularly with Neem Oil to kill the eggs or with Bt to kill the caterpillar when it chews into the plant. I have heard of using netting but I don't know how well that works.
We have had Leaf Miner on my allotment site in the UK for some years now. Please appreciate that any timings I can offer regarding the life cycle are UK timings. The fly appears in March / April having overwintered in the soil. The female fly lays her eggs near the bottom of the young allium plants. She will also make puncture wounds on the plants stem and feed off the sap. The eggs hatch and the larvae begin to feed off the leaves then work their way into the stem of the leek or bulb of the onion. The flies pupate after a couple of weeks and in September/October emerge again as flies starting the whole process again. They will eventually hibernate and reappear in Spring.
In the UK there are no sprays available for domestic growers the only effective alternative is to cover the crop as soon as you have set it with in my case enviromesh supported by blue water pipe hoops. I have tried scaffold netting but it has a seam running down the middle which will let the fly in. My wife sewed this seam up which was somewhat effective but not as good as envireomesh. I have tried to upload a picture of one of my nets . I this instance its covering carrots but is the same principle.
On my site we also suffer with Downey Mildew and white rot but tha's for another day on how I combat those.
That blue water pipe is endlessly useful. I was initially advised to use bricks round the ends to hold it, but I find a bit of wood stuck in the end makes a good peg to hold it down. It will hold a cover for anything from strawberries to seedlings. One year I noticed the end was not closed off properly and wondered why the birds were not taking advantage to get at the strawberries. I had used a piece of old net curtain that kept it nice and warm in there, and found the cat curled up in it enjoying the warmth.