I think it takes a while for zoysia to get fully established. I noticed that they wilt rather quickly if gone too long without water early on. 8 weeks isn't long enough for sure. Maybe the sprinklers are off or something. Put tuna cans everywhere and see how much water they get during your normal watering time and adjust it accordingly. Once established, they are hard to get rid off compared to bermuda and st augustine in partial shade condition like yours esp during terrible drought.

You should have been keeping the sod moist by watering it LIGHTLY, three times per day, for the first 3 weeks after putting the sod down. It doesn't sound like you were doing that. Regardless, it sounds like it's wet enough now. Zoysia has a fatal flaw in my book. When it goes bad, it doesn't seem to matter what month it went bad, it remains dead looking for the remainder of the season. Then in April (or March for you in FL), it finally comes back like nothing ever happened. So whether your problem was too much water or not enough water, the grass is likely to be "dormant" for the rest of the year. Can you lift any of the squares of sod or are they all knitted down to the soil by new roots? Did you get watering instructions from the sod installer? If so, what were they? Have you measured the output of your sprinklers? You can do that by timing how long it takes your sprinklers to fill several cat food or tuna cans placed around the yard. My sprinkler takes 8 hours to fill the cans. My neighbor's high flow system takes 20 minutes. It all depends on YOUR system. Once you have that time, that will become the time you water every time you need to water. It might seem like a long time to water but you're not going to do it very often. For example I did not water my Texas desert lawn until mid July this year. Why? Because the roots on my lawn were deep enough to capture deeeeeeep water from the occasional rain we got. But my yard might have been an exception for other reasons. Here's the basic watering plan for the US (except for the triangle from Green River, UT down to Palm Springs, CA over to Junction, TX). Water deeply and infrequently. Deeply means a full inch at a time. Infrequently means with temps in the 90s or above, once per week. With temps in the 80s, once every 2 weeks. With temps in the 70s, once every 3 weeks. What this does is develop very deep roots which can take advantage of every rain storm for a good long time. It also allows the soil to dry out completely at the surface which prevents new weed seeds from sprouting. Proper watering is quite often the last correction people need to make to get their lawn to the next level of perfection and stop using herbicides to kill weeds. Why did you pick zoysia instead of the more normal bermuda or St Augustine?

Either lack of water or disease. Whatever you do, it will not respond this season. And whatever you do, it will look great in April. That's how zoysia works.

Here is a great flow chart that can be used for all lawn problems . You may want to print this out and save it for future use . This is the time of year when mole crickets have hatched and are hungry . They love to attack bahia and zoysia roots . You can test with soap and water . It is critical to treat IF you find the critters , not if you "guess " because of the brown spots . You can save your lawn . Just search on solutionsforyourlife.com for products to use . Here is a link that might be useful: LAWN PROBLEMS .... dying or dead areas in the lawn