If he was arrested last Wednesday and sentenced today with credit for time served, the math works in his favor and release could come very quickly, possibly today or tomorrow depending on how the jail processes the paperwork.
Here is how to think through the timeline. A 7-day sentence with credit for every day since last Wednesday means the time served calculation covers most or all of the sentence depending on what day today is. If today is Wednesday or later, he has already served 7 days and the sentence is technically complete. If today is Tuesday, he is at 6 days with one remaining.
The catch is that jail releases do not happen the instant a judge signs paperwork. The court has to transmit the sentencing documents to the jail, the jail has to process the paperwork through their system, and the release has to be scheduled and executed through the booking department. That administrative process can take anywhere from a few hours to the better part of a day depending on how busy the facility is and what time the paperwork arrives.
Most jails process releases within a few hours of receiving court documents during business hours. If the sentencing happened late in the day, there is a reasonable chance the processing rolls into the following morning.
Call the jail's booking department and ask about the status of his release processing. They can confirm whether the paperwork has arrived from the court and give you a realistic window for when he will be walking out. Have a ride ready and stay reachable so you can be there when it happens.