For new grass growing from seed, you are supposed to keep the top 2 inches of soil moist at all times. I had to do this for the past 6 weeks. I started by watering manually, then experimented with a bunch of different sprinklers. The side lawn was pretty much rectangular except for a part at the end. It was difficult for standard, cheap oscillating sprinklers to cover because tree branches hung over the center part of the lawn. The lawn was about 60 feet across and perhaps 15 feet wide.
The best sprinkler was a pulsating sprinkler, an old Melnor that the previous owner left me. It was all plastic, but it worked great -- you could adjust the feathering, the distance, and the circular area that the water would cover.
I let the water from one hose go through a "Melnor XT Mini-Turbo Oscillating Sprinkler with One Touch Width Control & Flow Control, and Rotation". This is a "different" looking sprinker, and it has what Amazon calls "4 Way Ultimate Adjustment." It was just OK, but better than other sprinklers. I could adjust the width, distance of the spray, and how far the watering pattern would go back and forth -- but it was a finicky unit. I spent hours getting the unit to work just right, and it would still leave dry spots of soil right in front of it. The best part of this small unit was that the water could pass through it to the above Melnor pulsating sprinkler. Using both of these let me water just about all of the new lawn.
I tried other sprinklers and was disappointed. I tried two different (inexpensive) oscillating Gilmor sprinklers from Lowe's and had to return both of them. The Gilmor sprinklers, including a Melnor pulsating plastic sprinkler, would not work if connected in series with one hose. My water pressure was fine, and the Melnor XT Mini-Turbo (what a ridiculous name) worked just fine.
I then bought a Gideon Two-Port Water Timer and set the timer so the bottom two sprinklers (on their own separate hose) starts at 6PM for 20 minutes. Then the top sprinkler starts at 630PM each day for 20 minutes, watering the top of the lawn. This way, each "section" of sprinklers gets the full water pressure available while it is on.
The Gideon timer has been working fine for a week. I did look online for a user guide but there are none to be found, and the website is really sad. It seems that the manufacturer is just a distributor of gadgets; no user guides at the website. I've scanned the user guide for anyone who needs it; here it is.