Im going to throw a little more at you.

First, I'm a state licensed applicator, with qualifications in turf, biting fly and tick, and outdoor ornamental, among 3 or 4 others that aren't relevant.

That all said my experience and recommendations are largely limited to the products I use. I buy product by the pallet, not by the bag from Skillins or Ace.

Some quick notes on grub control chemicals:

Acelepryn is a lot less dangerous to pollinators than neonicotinoids (Merit, a Bayer product, is the most common of those products, but there are 4 or 5 common ones.) Acelepryn is still on patent, so only Syngenta makes it, and it's more expensive, so most DIY weed and feeds are still using neonics.

As has been explained to me by various groups in the trade, this is the last year for neonics in Maine, because they are so hard on bees. But the state let them go this year, because Acelepryn is set to come off patent the end of the year, so the price should fall after this season as other manufacturers begin to produce off brand versions.

Personally, we still sell Merit, because it's cheaper its what a lot of people want, but we've swapped almost all the applications we make over to acelepryn over the last few years, because it has a better PR image, and frankly it works better, is less dangerous to us and has a larger application window making it easier to get out across a varied client base.

So my advice is for an Acelepryn based product based on an average year, because that's where I'm most versed.

With Merit, off the top of my head, anytime in late May through maybe the 3rd week in June, earlier if it's a warm spring. You want to get the stuff down a couple weeks before you start to see a lot of Japanese beetles.

Most grub control applications work better if you water them in. Most of the commercial labels I work with specify watering in. So ideally, on anunirrigated lawn, you'd make your application right before a light rain.