The .com zone file is updated every few minutes. Caching behaviours will vary significantly. Frequently a significant fraction of traffic can be using new nameservers within minutes, with a long tail of traffic with older information.
Each TLD does their own thing. For example, last time I checked, .ca only seemed to be serving a new zone file every few hours. How long new nameservers take will depend on your luck in terms of where you are in their refresh cycle.
Each TLD does their own thing. For example, last time I checked, .ca only seemed to be serving a new zone file every few hours. How long new nameservers take will depend on your luck in terms of where you are in their refresh cycle.