I think it was at Botcon that they confirmed that season 3 has been in development since May so I guesstimate it should premiere around the same time as last year i.e. Christmas, that would give it sufficient lead time untill the next movie as well. Plus we have seen and heard of TFA characters that haven't been seen onscreen yet (besides Oil Slick).

SDCC is 3 weeks away so there will probably be more info released then.