The answer is, not unsurprisingly, "it depends." VPNs, despite what commercial VPN providers will tell you, were not designed to hide the originating source of the traffic. They were designed to offer confidentiality and integrity between two network endpoints.
To answer your question of "does it matter what my ingress point is", well, there's a few issues to consider:
- Does your ISP log individual TCP/UDP connections? If so, the connections can potentially be correlated.
- How can you be certain that your VPN provider does not log inbound connections?
- Can an attacker see both the inbound and outbound traffic from the VPN?
That being said, if you really want to avoid someone discovering the source of a website being built, you need to consider a lot more.
- Will you register a domain? How will you pay for that?
- How will you pay for your VPN? Will they turn over billing records associated with connections?
- Will you use a paid hosting service? How will you pay for that?
- If you forget to use your VPN even once, you'll leak your home IP to the sites you connect to (admin panel for your hosting, etc.)
Depending on your threat model, consider what happened to Ross Ulbricht when he was running Silk Road. (And that was using TOR, which is designed for far more anonymity than a VPN.)