If I had those seeds, I would be starting some for sure. Unlike bulb onions, leeks are not day-length sensitive. They seem secure in their identities as perennials, and kind of poke along all season, slowly getting bigger.

King Richard is a "summer" leek that never gets more than a half inch in diameter for me. However, he's a great cut-and-come-again candidate. Each time you pull a leek, cut off the bottom half inch with roots and replant it. You will double your harvest this way.

Your other variety is a winter leek and I think you are right on schedule for starting the seeds. I would also start composting some organic fertilizer so you will have a very rich medium to transplant them to in a couple of months. With plenty of nutrients and moisture, these will grow into big, fat leeks to harvest just before your first hard freeze.