It sounds like you have been approved for the advanced tax credit starting in August? I was able to claim the HCTC a couple of years ago. I didn't bother with filing the paperwork to get the advanced payment. I filed my taxes with form 8885 and received the credit in my tax refund. On that form, you state the months you are claiming the credit for. One thing to note: even if you file your taxes electronically, you have to mail in evidence of your qualification for the tax credit (invoices and payments of your healthcare premiums, PBGC info).
I was pleasantly surprised that having my company declaring bankruptcy would have such a big financial benefit to me!