I finished up a BT with the final payment in June. My card is on a zero-percent purchases year that expires in August, so no interest on purchases, Q2 wasn't interesting, ended up never using it for gas, other cards give points on Lyft/Uber. Card went to zero for that June 17 statement.
I started using the Discover again for dining, and first transaction was 16 July, for $1.20. The statement date is 17 July, and since the $1.20 was the only amount that posted, the statement printed with a Small Balance Credit immediately provided, zero due. There was nearly $7 of Pending transactions on 16 July also, but those were disregarded in the automation to zero the statement amount.
Discover acts pretty quickly. 
For first time in awhile, my 8k Disco has no bt offers
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