I (25+ years ago) put in a new lawn after having a house built.
I planted plain oats with the EXPENSIVE perennial grass seed to act as a nurse crop.
(If I do it again, I'll spread clover seed too.)
The oats gave good shelter for the tender lawn seedlings, prevented erosion during and after their life-cycle.
The next year, I had an acceptable start to my new lawn.
For what it is worth, I did not know where the sidewalks were going to end up so I made paths with pallets. The grass /oat seeds grew between the slats and I could chose my sidewalk placement later.
