Seeding is tough in July, as you know. Is your lawn mostly clover and weeds at this point? If so, i would kill it all off with Roundup rather than a selective herbicide like WBG. Grass seed and young seedlings are very sensitive to WBG, so if you use WBG, wait four weeks before you start your seeding.

I mostly agree with maynard. I would wait a few weeks to start that plan.

If a total redo is in your budget, spray with RoundUp to kill everything. Then continue to water on a daily basis to try and sprout all the sticker and weed seeds you can. After a week of daily watering, spray Roundup again to kill any new weeds you started with the watering. You can collect the stickers by dragging some fabric over it. Drag until the fabric is full of stickers and then scrape them off somewhere so you can collect them and burn or discard them. (I never said this would be easy). Continue dragging until you are fairly happy that all the stickers are gone. This dragging might be a superfluous step depending on your stickers. Down here in Texas the stickers will not come back if you have a dense lawn.

After you have done that, it is best to run a vertical blade tool like a power rake, slit seeder, or verticutter to chop up all the grass and weeds that were there. Rake up all that chaff and compost it.

Now you have a seed bed. Now is the time to flatten the ground. Do not rototill it or you will be facing an increasingly bumpy lawn for 3 years. Just scrape the hills into the holes and you are good. Scatter the seed and roll it down with a water roller (rented).

Water the seed 3x per day for 5 minutes to keep the seed moist. Do not saturate the soil. Continue this until you get 80% germination. Rye grass comes up in a week. Fescue comes up in 2 weeks. Kentucky bluegrass comes up in 3 weeks. This little fact can be a problem if you have a triple seed mix and stop watering after the first seed comes up. Then all you would have is rye.

When the grass is up and maturing, you can start to back off on the watering frequency and start watering longer. Eventually with a mature lawn you will be watering one full inch per week (when temps are above 90 degrees F), every other week (when temps are above 80 degrees), and once every 3 weeks when the temps are lower than 80 degrees).

Fertilize with chemical fertilizers on Memorial Day, Labor Day, and, for you in SD, probably don' wait until Thanksgiving. Maybe Halloween for the final app of the year. These are timed so that you don't apply in early spring or mid summer. Or you can fertilize with organic fertilizer any day of the year.