It all depends on:
1. How small is the network that could vary from 2 network points to 50 points
2. What sort of network, simple cabling or some specific VLAN configurations?
3. Security Measures?
4. Only cabled or Wireless too?
5. Want to connect to outside world or just internal connectivity
Once you are clear with this, the exact timeframe can be drawn out which could be 1 days to 10 days or so.