Here is the big dead spot that's been this way since I moved in

You can apply corn meal any time, day or night, rain or shine. Once you see it work like that, it's easy to get excited about using more. It works both as a fertilizer and the anti fungal. As a fertilizer there are better organic fertilizers; however, if you use any of them more frequently, everything seems to get better. Morpeuspa has tried to overdo organic fertilizer and was not able to do it. He fertilized with two organics every weekend all season long. No problems. I did something similar by using corn gluten meal once a month all season. No problems - other than lots of grass to mow. As for watering, use temperature as your guide. With temps in 70s water no more frequently than once every 3 weeks. I stretch it out longer, but I always water deeply when I do water. Ideally you'll get enough rain in the fall and spring that you won't have to water again until June or July.

Only if it's dry. It's certainly optimal not to allow the grass blades to stay consistently wet, but it's absolutely critical that the sod stay moist for the first few weeks until it roots solidly (then back off watering slowly to give the roots time to adjust and grow in). So in a balance between the two, if the sod is dry, it must be watered regardless of the time of day. If moist, water at another time and try to go into the night-time period with dry blades. But realize you're going to end up with dew in all likelihood anyway and, frankly, a lot of the ballyhoo about wet grass is mostly applicable to very hot weather and consistently watering at night. Which you clearly have no plans to do. :-) I'll tell you a secret. You know, just between us here on the Internet, nobody else will see. :-) I water at night because the Sun is down, the winds are low to zero, and evaporation is near-zero. But since I'm only watering every fifteen days--absolute maximum (I actually watered exactly once in 2019)--I'm risking exactly nothing in terms of fungal disease on my lawn. It simply doesn't happen often enough to matter and I've established deep enough roots for my lawn to take care of itself (bluegrass, in Pennsylvania, a very different prospect to yours). It's not the fact of doing so that matters. It's the frequency.

From the WSU extension service publication: "Kentucky bluegrass is the most commonly used lawn grass in the United States. Kentucky bluegrasses, in general, are not well-adapted to western Washington’s soil and climate." From OSU discusson of seed blends suited to PNW lawns: "Kentucky bluegrass is the most common lawn grass east of the Cascades, but disease susceptibility makes it poorly suited to locations west of the Cascades." And from article written by Tom Cook, Professor Emeritus, OSU on Poa pratensis (KBG): "Kentucky bluegrass use in the Pacific Northwest reads like a ‘Tale of Two Cities’. In areas east of the Cascade Mountains it has always been the dominant turfgrass. With a climate defined by hot summers, low humidity, cold winters, and calcareous soils, bluegrass grows incredibly well. West of the Cascades, bluegrass has been tried repeatedly without much success. The first major effort to use Kentucky bluegrass in western parts of Oregon and Washington started around 1960 when sod production began. Following the lead of sod growers around the USA, farmers planted mixtures containing ‘Merion’ bluegrass to increase sod strength. Early plantings were noted for their susceptibility to Stripe rust. They typically failed in 3-5 years being replaced by indigenous grasses and often with annual bluegrass. Gradually, people quit trying to plant pure Kentucky bluegrass and today you will generally find bluegrass only in seed mixtures marketed nationally and in some sod blends." Despite what some east coast responders may erroneously assume, KGB seed or seed blends are NOT recommended for this area!! Local seed mixes - and regionally prepared mixes are highly recommended over national brands - rarely include any in their blends and local sod farms do not grow it. The climate and growing conditions of the PNW are pretty unique, especially west of the Cascades, and it is highly unusual for anyone who has not lived or gardened there to speak to them with any kind of knowledge or accuracy.