There is no definitive way to tell when propagation is complete for you as it depends on three factors: TTL, your ISP, and geographical location. However, you may use online DNS checkers in order to track if the DNS record information propagated against multiple nameservers located in different parts of the world.
DNS Checker provides a free DNS lookup service for checking domain DNS records against a randomly selected list of DNS servers in different corners of the world. As a result, you will get DNS data collected from all locations confirming whether a website is completely propagated worldwide or not.
Here is the list of the most popular DNS checkers:
App Synthetic Monitor
G Suite Toolbox
There is another way to check if the DNS propagation is completed for you. You need to run one of the following commands from your PC, laptop or other devices:
What we need to know from the results is the IP address your domain is resolved to. If it's the IP address of the new server, probably, the DNS propagation is complete for you. If the IP address belongs to the old server, you need to wait for the DNS propagation to complete.