New Tiftuf Sod - Questions on next steps

Thanks to this forum for the wealth of information provided. I've been lurking for years when I had a TTTF lawn. I recently moved to SE Virginia (8a) and laid a little over 2,000 square feet of TifTuf 7 days ago. Everything has gone pretty well. The prep work went well, sod looked "ok" when it was laid, and I've watered twice a day (morning and around 2:00 PM) for the last week. Overall, the grass has rooted pretty well as I would need to pull hard to lift a square, and much of the lawn has turned slightly greener than it was when it arrived.

However, over the last couple days, there is a slightly increasing amount of brown in certain parts of the lawn. I've included photos. It isn't too bad, but i've been watching it over the last 72 hours and it seems to be growing slightly. It seems to be focused in areas of the lawn that sit lower and hold irrigation longer (leveling is in my future). The weather has been fairly cool for this time of year with daytime temps reaching 70 and overnight lows down to upper 50's. So not exactly the weather I would expect fungus, but I have been watering frequently enough for the lawn to stay moist. I have a mostly clay soil that holds water more than I am accustomed to. I am not seeing the "cobwebs" I would expect with dollar spot.

It is expected to be warmer next week which I hope will perk up the lawn and work through any fungus, so my plan now is to:

• Reduce watering to only once a day in the morning
• Monitor current spots for any further growth
• At two weeks, apply a starter fertilizer. I am awaiting soil test results, but the previous owner did not do any kind of lawn care so I imagine I'm deficient in the normal areas. I did not apply a fertilizer before the sod went down.

Questions:

• Does this look like fungus? I have some DiseaseEX, should I apply now? Any harm to the new grass
• Maybe insects? Put down an insecticide?
• With warm weather arriving, should I feed the lawn now and not wait another week? Will that help?

Any other comments or suggestions are greatly appreciated. I'm trying to be patient with the warm weather on the horizon and realize it's only been 7 days, but I don't want to wait if this is the start of something bad.

I've included a before photo of the lawn I inherited a few months ago, and the lawn as of today.