Usually they upload it the next day.
I've recently done my (re-med) chest x-ray from Apollo Chennai and when I called them to follow up on the same, they've informed me that it will be uploaded the next day, because, the radiographer has to convert the x-ray image into a specified format and this will be emailed to the medical officer.
I suggest that you call the customer service and they will re-direct you to the concerned personnel. Give them your Client ID(from the receipt which you received) or mobile number, and they will be able to confirm the status. Don't worry. They're all quite helpful.