Yes, immediately. Once the restitution is paid in full there is no waiting period before you can deposit funds into the inmate's trust account. The two things are handled through entirely separate systems and one does not create a hold on the other.
Restitution payments go to the court or the victim compensation fund depending on how the order is structured. Commissary deposits go directly into the inmate's trust account through whatever platform the facility uses, whether that is JPay, TouchPay, or another service. Those systems operate independently and a restitution payoff on one side does not trigger any kind of processing delay on the other.
If you are making the restitution payment and the commissary deposit on the same day, you can do both in whatever order makes sense for you. The commissary deposit will post to the account on its normal timeline, typically one to two business days after the transaction is processed, regardless of what else happened that day financially.
The one thing worth confirming is that the restitution payment has been properly recorded and receipted before you consider that obligation fully closed. Keep documentation of the payoff in case any question arises later about the balance. Court and restitution records do not always update instantly, and having a receipt protects you if there is ever a discrepancy.
Beyond that, the books are open and ready for a deposit whenever you are ready to make one.