What's the best time to sign up for Direct TV?

I'm considering signing up for Direct TV. I'm not in a rush. I was wondering if anyone has noticed a trend as to whether or not there is a seasonal trend for their best promotions?
Get the free Apple 4K TV streaming box with 3 months prepaid Direct TV streaming before the deal ends....right now.

Direct TV streaming is $35/mo and the apple box is worth $175.