If you have changed nameservers, it usually takes 24-48 hours for a domain to fully propagate. This means that you might not see your website as active during that period. It might show up for a few minutes to a few hours and then stop working for a few minutes to a few hours until the 48 hours have passed. We're unable to speed up this process as it doesn't depend on us.
It depends on your Internet Service Provider (ISP). It might update within minutes for your neighbour but take up to 2 days for you.
The reason for this is that the local routers your ISP runs off of update at different times.