2018 or 2019 Audi SQ5 Lease

I have a 2017 Audi Q5 Premium Plus in SF area with lease ending August 2019 (less than 5 months left). Will probably lease the same or upgrade to SQ5 if I can make the numbers work.

When is the optimal time to start negotiating a new lease? 2 months before lease ends?

Anyone have any recent deals they can share for either Q5 Premium Plus or SQ5 or what you think would be a realistic deal?