I wish I could, but I honestly have no idea! My plan for Beta 2 is for it to go up to the fifth Gym (for a frame of reference, Beta 1.1 goes up to the second Gym), which will include quite a bit of story stuff in between as well. I've recently completed the third Gym, and progress is going relatively fast, so if I were to give an estimate I'd say two months wouldn't be overly ambitious, but no promises!
Thanks for you support, it means a lot!