Some of our law firm's company clients received cleared checks written out to USCIS in connection with their H1B quota cases filed on Apirl 3, 2017. This is clear indication that those particular cases have been accepted by USCIS. One of the first things USCIS does after receiving a case is to process the filing fees. USCIS does not deposit the filing fee checks if they don't accept the case.
What happens next: USCIS will send hard copy receipt notices. This is done via regular U.S. mail and may not get sent right away. It may take a few days or even a few weeks to receive the hard copy receipts. In our past experience, receipts arrive from late April all the way through July.
What if a case is not accepted: the entire filing packet, including the filing fee checks, will be returned to the employer's attorney via regular U.S. mail. This doesn't happen right away and typically takes several weeks to receive.
On April, 7, 2017, USCIS announced that the H1B cap limit for fiscal year 2018 has been reached. However, unlike announcements made in previous years, USCIS did not inform the public how many filings were received, nor did USCIS discuss a lottery selection process.