Good points all. No shrubs as far as I know. I would guess that unless the owner makes unexpected demands I'll only be blowing trimmings off the front lot.
The biggest problem here is that I don't have a clue how long it would take to mow that field. I don't even have enough experience to make a ballpark guess.
One trick I have done to learn is to tell them the truth, "I do not know how long it will take but here is what I will do. I will cut it one time for______ and give them a very low price if you will let me cut it once and see how long it will take and let you look at the job and see if you are comfortable with my work and then I will tell you what I will do it for from now on." I have picked up business that way.
With my two Kubota zero turns we have cut 4 acres in under and hour. On other jobs we have worked an hour on less than two acres. There are many many variables that figure into time.
Variety of grass, height of grass, roughness of ground, are a few.
On very smooth ground and in something like centipede that is not real tall we can probably cut 5 acres on an hour. On the other hand Pensacola Bahia that has not been cut in 10 days or more will slow us to a crawl many times.
With that knowledge in mind I have still bid yards way over and way under in time without putting the mowers on the ground and seeing.
If they won't bite on that measure the area some way. Then know how many square feet it is approx. take some where you cut that has similar grass and measure it. See how long it takes you to cut it. Then divide the smaller place into the larger place and figure time from there......