Your domain's TTL values determine how frequently your DNS records get updated. Lower values mean your DNS gets updated more quickly — which means if you make changes to where your website or email are hosted, they take effect more quickly.
You can change your domain name's TTL values but (unfortunately) there is no value that lets your DNS changes take effect immediately. Most of these changes take effect within 2 hours, but can take up to 48 hours.
It can take up to 48 hours for your changes to take effect across the internet.