In general, a locksmith will take 15 – 20 minutes to reach you, but this depends on a number of factors.
Traffic and weather conditions, roadworks, and the time of day or night that you require services will all impact how quickly a locksmith can get to you. If a locksmith is currently at a client and nobody else is available to assist you, you will need to wait until that job is complete before you can expect to be helped.
If you are in an emergency and need urgent assistance, you could always contact another local locksmith if your preferred professional is unavailable. Just make sure that you do as much research as possible to ensure they can be trusted and have the experience you need.
In most instances, however, locksmiths work in teams, so it’s highly unlikely that nobody will be available to assist you. Just know that there is no need to wait an hour or more for a locksmith to reach you unless you are contacting someone who operates in a completely different area or city. If this is the case, be prepared to possibly pay extra for travel costs.