I think I take it down when it's below 100. Or whenever I feel comfortable myself being outside during the day :)

It depends on what you are growing. If you are growing succulents, I'd wait until the equinox in late September, to prevent burning. Then, over the winter and spring, their skin can become accustomed to full sun for next summer. (except all those tender South African succulents that cannot take our afternoon sun at any time of year). Good luck; trial and error is how I learned (and am still learning).

I'm hoping to grow vegetables. I used to garden in the high desert and did pretty well but this is a whole new experience. Life was busy and I didn't get my shade cloth over the tomatoes and peppers until late June, and they haven't recovered although the peppers are starting to show a bit of new growth. I planted zucchini and cucumbers couple weeks ago, they sprouted and look okay so far. I guess I'll take the shade down in late September.

Don't worry if things burn up. A pack of seeds is cheap. Live and learn. If you start tomatos now you will get another bunch and they may go through a good portion of the winter and then the few that make it will come back to life in spring aka late winter. I would say in general once we hit 100 or less on average (sometime after mid september) you're good to go on removing the shade cloth. But maybe ease into it. I generally recommend people dont bother with shade cloth for the veggie gardens and that they just grow with the seasons. If you get a few that make it through the heat and or cold, save the seeds. Those are the ones you want to keep.