The same contact within Hasbro here in the Asia region who gave us this info way, way back about waves 2 & 3 before they came out;
Has just told us to expect Speeder Bikes/Jabba in August and confirmed two speeder bikes/biker scouts and one Jabba per case. Nice!
A smart case pack especially as not many are army building Jabba : )
Please note info can change, so should be treated as a rumour but they certainly came through for us before. Checked with other online retailers and they have said all they have been told is September, and no case pack info revealed to them at all. Time will tell.