Timing is perfect for direct sowing spinach b/c it likes cold. I’d just cover the row with a lite fleece and check periodically for slug damage. Spinach is pretty hardy and the fleece is very nice for reducing moisture loss through dessication yet it still breathes - unlike poly.
I score the seeds a little in a morter and then soak a day and then sow. If you don’t score them then I’d let them soak longer - several days. That’s been my experience.