Can I start a ryegrass lawn renovation in early September?

Looking at doing a full lawn Reno with sand up in Napier, Hawke’s Bay with perennial Ryegrass. I have just applied some Etho to try kill off the weeds that have come through. What are the thoughts on doing a full Reno the weekend of the 12th September or is that too soon?. I have a job to do down in Wellington so that’s my only available weekend but worried it is to soon with the soil temps.
What are the thoughts?