I'd recommend targeting August for an overseeding/renovation date. If your mix had that much annual ryegrass, I'm guessing the 40% remaining is garbage--and you probably have a bunch of crabgrass, so I would favor nuking the whole thing with roundup and then reseeding. There is nothing wrong with the way you did it. Plenty of people want a lawn fast, even though it's not the best season to do it. A useable temporary lawn is better than a weed lawn.

Here's some Wisconsin info:

https://cdn.shopify.com/s/files/1/0145/8808/4272/files/A3434.pdf

I’m not sure I’d want to kill all the other types of grass that were in the mixture. Could I just wait for the ryegrass to die and then overseer the existing grass?

The rest of the mixture was 20% perennial ryegrass 10% Kentucky blue and 10% red fescue.

The problem is, 80% PR or AR means almost none of your stand is KBG CRF. PR/AR quick germination and establishment really outcompetes the other two. PR/AR are both used as a nurse grass up north but too much % in a mix and it will completely dominate the stand. Moreover, trying to overseed desirable grass into a healthy annual ryegrass stand is a losing proposition in my book.

Okay - it will just be a hassle to kill everything, cultivate, smooth out the yard and then reseed but I understand your point. We just have 5 acres to do this again. I spent so much time watering and moving sprinkler but I guess you live and learn!!

Bump - anyone else?