For such a task I try to keep 1000 (A full stack) on hand, but as its you first horde day you probably wont need that much. Sadly each wood spike is 100 wood, and takes a while to craft.so you might not have time to craft all you need for Day 7, so I'd recommend gathering all the plantfiber and rocks and feathers you can, and stockpiling all the cobble you can.so you can make more arrows if you run low, and repair your walls.
Its probably too late to put wood spikes around your log spikes.are the log spikes upgraded at all? they don't do much damage, so you'll have to be up there all night raining arrows down. I'm not sure what I should be doing at night, but I've been tunneling underground at night towards the nearby lake with the intent to flood said tunnel to provide an underground pool for my little shelter. I never found an xbow blueprint or any proper firearms, but I do have ~30 rounds of blunderbuss ammo, ~300 iron arrows, and ~200 stone arrows.
On the ground is a perimeter of tier 2 log spikes approximately 4 layers deep. A lip of metal trusses caps the structure. I've got a simple ~5x5 wooden shelter that I've subsequently gilded with cobblestone. I'm not sure how heavily I'm going to be hit. I'm at the end of day 6 in my first solo game and about to enter day 7.