You need at least six months of established credit reporting to a CRA to establish a credit score.
But that make take 7-8 months from initial date of account to show on his CR due to delays in creditor reproting, and CRA posting.
Assume 8 months max from account opening date and it will pop up.
If it is his only CC, let a very small balance report, even $1.
You don't want 0% utilization.