The best moment: deploy, site is online, client is happy.

The worst comes 8 months later: "Filip, the site doesn't work" or "we got hacked."
A site isn't a poster - it's a machine
If you don't maintain it, it slowly decays. Quietly.
What happens when nobody touches a site
- Security vulnerabilities pile up
- Forms stop working silently
- Speed degrades
- Content goes stale
- Something simple breaks (expired domain, SSL, hosting)
What maintenance actually means
| Activity | Frequency |
|---|---|
| Check site works | Weekly (automated) |
| Backup | Weekly |
| Software updates | Monthly |
| Check forms and links | Monthly |
| Content updates | As needed |
| Analytics review | Monthly |

Two maintenance models
You maintain - if you have CMS and someone technical. Still need help for bugs and updates.
Monthly support package - typically €30-100/month for smaller sites. Sounds like a cost until you pay €300 for an emergency fix.
Real example
WordPress client refused monthly support. 10 months later - hacked, Google flagged as dangerous. Recovery cost far more than a year of maintenance.
Conclusion
Launch is the beginning, not the end. When talking to a developer, ask not just "how much to build" - ask "what happens after" and "what if something breaks."