Temp titrations in the early weeks

[Lark60]

I have 5 polish chicks that are 1 week old today. I will be adding new chicks from the incubator next week. I live in Tucson Arizona and so the air is hot and dry. The brooder is currently at 90 degrees for the 1 week old chicks and my question is what temp should I set the brooder next week when the new chicks hatch? Do I raise it back to 95? Leave it at 90 and then titration down based on the new chicks age? I don’t have the ability to have 2 brooders.