Waiting for receipt no for H1 transfer which is applied on premium processs

My employer has applied for an H1 transfer (on premium process) on 21st May 2018 and its reached on 23rd May 2018. Still I am waiting for receipt no. Is it taking more than 15 days just to get the receipt number/case number for your submitted application at USCIS office? Please let me know if you heard or know about this situation. Thanks in advance.