I had to refresh my memory on this, but a quick google search says:
Cyrus will awaken and provide his services only with the gate closed and no visitors. To use him, four conditions must be met:
100,000 Bells worth of items have been sold to Reese.
50 pieces of furniture have been cataloged (found at the Nookling Stores).
10 pieces of clothing cataloged (from the Able Sisters).
The player has played for seven days.