What are the chances that there will be another BOGO promo in a few months?

I currently have two Unlimited Premium lines on an annual plan, and it's set to renew on November 5th.

My SO would be perfectly fine with Unlimited Starter, meanwhile I need Unlimited Premium, so the BOGO promo would be ideal for us when we pay for another year of service.

I'm just wondering if there will potentially be another BOGO special around that time, or if there is a way to sign up for the BOGO plan now and just add the additional 12 months to our existing time left?