Heya @FelixLeiter!
Thanks so much for your patience while I solidified these answers for you. As for Harley Quinn and the Birds of Prey #3, that should be available on the service on April 6th. We are still in the process of confirming this however.
As for your question concerning the “6 months after hitting stores” timeframe, it works as it does with any other digital retailer, in which that is considered a soft 6 months. This is the same structure that was used when it was a 12-month release delay as well. There are numerous reasons that this may be the case, which is why we utilize the soft 6 months rule of thumb.
I understand that you are upset and apologize for any misunderstanding or confusion that might have happened. I hope that this clarification helps to alleviate any further misunderstanding. If it doesn’t, however, please let us know if you have any further questions.