Your V5 characters can use the dating channel (matchmaker) 48 unpaused hours after becoming adult. The matchmaker shows an angry face if your V5 charaters are too young to use the dating channel.
You can use the dating channel three times a day (that's at any time they're awake.) The matchmaker will appear to be asleep, if you've used the dating channel three times already that day. (But if you change the time on your V5 clock to make your V5 characters asleep, then change it back to make them awake again, you can use the dating channel three more times.)