The simple answer is "yes" - as soon as possible.
You have no idea how many keys the previous owner or tenant gave away to friends, family or neighbours. Aside from the obvious risk to your security this poses, in the event of a burglary, the majority of insurers will refuse to pay out if there is evidence that the thief has let themselves in.
Changing the locks when you move is usually the last thing on your mind, after unpacking, cleaning, redirecting mail, and shopping for new cushions. Furthermore, Locksmiths are not free, and given the rising cost of moving house, you may be tempted to ignore the risks.
Changing the locks and having new keys cut yourself can be cheaper, but still requires an investment of time and money which many new homeowners put off indefinitely.
2 in 3 ignore the risk
Based on these factors, the attitude among homeowners is one of denial, that it will never happen to them.
A recent survey revealed that two thirds of homeowners fail to change the locks when they move. Not only does this carry the risk of invalidating their insurance where a burglar has used an old set of keys, there is the additional risk that the locks themselves are inadequate.
Even if a break-in has occurred without access, insurers will be unlikely to pay out if the locks and other security measures protecting the house are not up to specification. You may also face higher premiums in future, not to mention the psychological impact burglary can have on your enjoyment of your new home.
Change home alarm codes
Alarm codes should also be changed when you move in, and remember not to pick something obvious. In 2011, a Hastings property was successfully broken into after the burglar guessed (or knew) the alarm code was. . . 1066.